diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..cf49ca2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.classpath
+.project
+.settings/
+target/
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
index eb50710..4e9d12f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -75,6 +75,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-gpg-plugin</artifactId>
+                <version>1.6</version>
                 <executions>
                     <execution>
                         <id>sign-artifacts</id>
@@ -148,37 +149,16 @@
     <dependencies>
         <!-- Production dependencies :: Default scope -->
         <dependency>
-            <groupId>it.unimi.dsi</groupId>
-            <artifactId>fastutil</artifactId>
-            <version>${fastutil-version}</version>
+          <groupId>com.carrotsearch</groupId>
+          <artifactId>hppc</artifactId>
+          <version>0.7.1</version>
         </dependency>
 
-        <!-- Test dependencies :: Test scope -->
         <dependency>
-            <groupId>org.easymock</groupId>
-            <artifactId>easymock</artifactId>
-            <version>${easymock-version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.powermock</groupId>
-            <artifactId>powermock-module-junit4</artifactId>
-            <version>${powermock-version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.powermock</groupId>
-            <artifactId>powermock-api-easymock</artifactId>
-            <version>${powermock-version}</version>
-            <scope>test</scope>
-        </dependency>
-        <!-- NOTE:  the "jdk15" classifier is "JDK 1.5+" -->
-        <dependency>
-            <groupId>org.testng</groupId>
-            <artifactId>testng</artifactId>
-            <version>${testng-version}</version>
-            <scope>test</scope>
-            <classifier>jdk15</classifier>
+          <groupId>com.carrotsearch.randomizedtesting</groupId>
+          <artifactId>randomizedtesting-runner</artifactId>
+          <version>2.1.14</version>
+          <scope>test</scope>
         </dependency>
     </dependencies>
 
@@ -190,7 +170,5 @@
         <!-- Testing versions -->
         <easymock-version>3.0</easymock-version>
         <powermock-version>1.4.8</powermock-version>
-        <testng-version>5.7</testng-version>
-        <fastutil-version>6.5.11</fastutil-version>
     </properties>
 </project>
\ No newline at end of file
diff --git a/src/main/java/net/agkn/hll/HLL.java b/src/main/java/net/agkn/hll/HLL.java
index cdfd3ad..688213a 100644
--- a/src/main/java/net/agkn/hll/HLL.java
+++ b/src/main/java/net/agkn/hll/HLL.java
@@ -18,8 +18,11 @@
 
 import java.util.Arrays;
 
-import it.unimi.dsi.fastutil.ints.Int2ByteOpenHashMap;
-import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
+import com.carrotsearch.hppc.IntByteHashMap;
+import com.carrotsearch.hppc.LongHashSet;
+import com.carrotsearch.hppc.cursors.IntByteCursor;
+import com.carrotsearch.hppc.cursors.LongCursor;
+
 import net.agkn.hll.serialization.HLLMetadata;
 import net.agkn.hll.serialization.IHLLMetadata;
 import net.agkn.hll.serialization.ISchemaVersion;
@@ -79,11 +82,11 @@ public class HLL implements Cloneable {
     // ************************************************************************
     // Storage
     // storage used when #type is EXPLICIT, null otherwise
-    private LongOpenHashSet explicitStorage;
+    LongHashSet explicitStorage;
     // storage used when #type is SPARSE, null otherwise
-    private Int2ByteOpenHashMap sparseProbabilisticStorage;
+    IntByteHashMap sparseProbabilisticStorage;
     // storage used when #type is FULL, null otherwise
-    private BitVector probabilisticStorage;
+    BitVector probabilisticStorage;
 
     // current type of this HLL instance, if this changes then so should the
     // storage used (see above)
@@ -347,13 +350,13 @@ public void addRaw(final long rawValue) {
                 if(explicitStorage.size() > explicitThreshold) {
                     if(!sparseOff) {
                         initializeStorage(HLLType.SPARSE);
-                        for(final long value : explicitStorage) {
-                            addRawSparseProbabilistic(value);
+                        for (LongCursor c : explicitStorage) {
+                            addRawSparseProbabilistic(c.value);
                         }
                     } else {
                         initializeStorage(HLLType.FULL);
-                        for(final long value : explicitStorage) {
-                            addRawProbabilistic(value);
+                        for (LongCursor c : explicitStorage) {
+                            addRawProbabilistic(c.value);
                         }
                     }
                     explicitStorage = null;
@@ -366,8 +369,9 @@ public void addRaw(final long rawValue) {
                 // promotion, if necessary
                 if(sparseProbabilisticStorage.size() > sparseThreshold) {
                     initializeStorage(HLLType.FULL);
-                    for(final int registerIndex : sparseProbabilisticStorage.keySet()) {
-                        final byte registerValue = sparseProbabilisticStorage.get(registerIndex);
+                    for(IntByteCursor c : sparseProbabilisticStorage) {
+                        final int registerIndex = c.key;
+                        final byte registerValue = c.value;
                         probabilisticStorage.setMaxRegister(registerIndex, registerValue);
                     }
                     sparseProbabilisticStorage = null;
@@ -423,7 +427,7 @@ private void addRawSparseProbabilistic(final long rawValue) {
         // NOTE:  no +1 as in paper since 0-based indexing
         final int j = (int)(rawValue & mBitsMask);
 
-        final byte currentValue = sparseProbabilisticStorage.get(j);
+        final byte currentValue = sparseProbabilisticStorage.getOrDefault(j, (byte) 0);
         if(p_w > currentValue) {
             sparseProbabilisticStorage.put(j, p_w);
         }
@@ -488,10 +492,10 @@ private void initializeStorage(final HLLType type) {
                 // nothing to be done
                 break;
             case EXPLICIT:
-                this.explicitStorage = new LongOpenHashSet();
+                this.explicitStorage = new LongHashSet();
                 break;
             case SPARSE:
-                this.sparseProbabilisticStorage = new Int2ByteOpenHashMap();
+                this.sparseProbabilisticStorage = new IntByteHashMap();
                 break;
             case FULL:
                 this.probabilisticStorage = new BitVector(regwidth, m);
@@ -541,7 +545,7 @@ public long cardinality() {
         double sum = 0;
         int numberOfZeroes = 0/*"V" in the paper*/;
         for(int j=0; j<m; j++) {
-            final long register = sparseProbabilisticStorage.get(j);
+            final long register = sparseProbabilisticStorage.getOrDefault(j, (byte) 0);
 
             sum += 1.0 / (1L << register);
             if(register == 0L) numberOfZeroes++;
@@ -607,10 +611,10 @@ public void clear() {
             case EMPTY:
                 return /*do nothing*/;
             case EXPLICIT:
-                explicitStorage.clear();
+                explicitStorage.release();
                 return;
             case SPARSE:
-                sparseProbabilisticStorage.clear();
+                sparseProbabilisticStorage.release();
                 return;
             case FULL:
                 probabilisticStorage.fill(0);
@@ -683,8 +687,8 @@ public void union(final HLL other) {
                         } else {
                             initializeStorage(HLLType.FULL);
                         }
-                        for(final long value : other.explicitStorage) {
-                            addRaw(value);
+                        for(LongCursor c : other.explicitStorage) {
+                            addRaw(c.value);
                         }
                     }
                     return;
@@ -698,9 +702,10 @@ public void union(final HLL other) {
                         sparseProbabilisticStorage = other.sparseProbabilisticStorage.clone();
                     } else {
                         initializeStorage(HLLType.FULL);
-                        for(final int registerIndex : other.sparseProbabilisticStorage.keySet()) {
-                            final byte registerValue = other.sparseProbabilisticStorage.get(registerIndex);
-                            probabilisticStorage.setMaxRegister(registerIndex, registerValue);
+                        for(IntByteCursor c : other.sparseProbabilisticStorage) {
+                          final int registerIndex = c.key;
+                          final byte registerValue = c.value;
+                          probabilisticStorage.setMaxRegister(registerIndex, registerValue);
                         }
                     }
                     return;
@@ -739,17 +744,18 @@ public void union(final HLL other) {
                         sparseProbabilisticStorage = other.sparseProbabilisticStorage.clone();
                     } else {
                         initializeStorage(HLLType.FULL);
-                        for(final int registerIndex : other.sparseProbabilisticStorage.keySet()) {
-                            final byte registerValue = other.sparseProbabilisticStorage.get(registerIndex);
-                            probabilisticStorage.setMaxRegister(registerIndex, registerValue);
+                        for(IntByteCursor c : other.sparseProbabilisticStorage) {
+                          final int registerIndex = c.key;
+                          final byte registerValue = c.value;
+                          probabilisticStorage.setMaxRegister(registerIndex, registerValue);
                         }
                     }
                 } else /*source is HLLType.FULL*/ {
                     type = HLLType.FULL;
                     probabilisticStorage = other.probabilisticStorage.clone();
                 }
-                for(final long value : explicitStorage) {
-                    addRaw(value);
+                for(LongCursor c : explicitStorage) {
+                    addRaw(c.value);
                 }
                 explicitStorage = null;
                 return;
@@ -760,8 +766,8 @@ public void union(final HLL other) {
                     // dest: SPARSE
                     // Add the raw values from the source to the destination.
 
-                    for(final long value : other.explicitStorage) {
-                        addRaw(value);
+                    for(LongCursor c : other.explicitStorage) {
+                        addRaw(c.value);
                     }
                     // NOTE:  addRaw will handle promotion cleanup
                 } else /*source is HLLType.FULL*/ {
@@ -774,9 +780,10 @@ public void union(final HLL other) {
 
                     type = HLLType.FULL;
                     probabilisticStorage = other.probabilisticStorage.clone();
-                    for(final int registerIndex : sparseProbabilisticStorage.keySet()) {
-                        final byte registerValue = sparseProbabilisticStorage.get(registerIndex);
-                        probabilisticStorage.setMaxRegister(registerIndex, registerValue);
+                    for(IntByteCursor c : sparseProbabilisticStorage) {
+                      final int registerIndex = c.key;
+                      final byte registerValue = c.value;
+                      probabilisticStorage.setMaxRegister(registerIndex, registerValue);
                     }
                     sparseProbabilisticStorage = null;
                 }
@@ -789,8 +796,8 @@ public void union(final HLL other) {
                     // Add the raw values from the source to the destination.
                     // Promotion is not possible, so don't bother checking.
 
-                    for(final long value : other.explicitStorage) {
-                        addRaw(value);
+                    for(LongCursor c : other.explicitStorage) {
+                        addRaw(c.value);
                     }
                 } else /*source is HLLType.SPARSE*/ {
                     // src:  SPARSE
@@ -798,12 +805,12 @@ public void union(final HLL other) {
                     // Merge the registers from the source into the destination.
                     // Promotion is not possible, so don't bother checking.
 
-                    for(final int registerIndex : other.sparseProbabilisticStorage.keySet()) {
-                        final byte registerValue = other.sparseProbabilisticStorage.get(registerIndex);
-                        probabilisticStorage.setMaxRegister(registerIndex, registerValue);
+                    for(IntByteCursor c : other.sparseProbabilisticStorage) {
+                      final int registerIndex = c.key;
+                      final byte registerValue = c.value;
+                      probabilisticStorage.setMaxRegister(registerIndex, registerValue);
                     }
                 }
-
             }
         }
     }
@@ -821,26 +828,28 @@ private void homogeneousUnion(final HLL other) {
                 // union of empty and empty is empty
                 return;
         case EXPLICIT:
-            for(final long value : other.explicitStorage) {
-                addRaw(value);
+            for(LongCursor c : other.explicitStorage) {
+                addRaw(c.value);
             }
             // NOTE:  #addRaw() will handle promotion, if necessary
             return;
         case SPARSE:
-            for(final int registerIndex : other.sparseProbabilisticStorage.keySet()) {
-                final byte registerValue = other.sparseProbabilisticStorage.get(registerIndex);
-                final byte currentRegisterValue = sparseProbabilisticStorage.get(registerIndex);
-                if(registerValue > currentRegisterValue) {
-                    sparseProbabilisticStorage.put(registerIndex, registerValue);
-                }
+            for(IntByteCursor c : other.sparseProbabilisticStorage) {
+              final int registerIndex = c.key;
+              final byte registerValue = c.value;
+              final byte currentRegisterValue = sparseProbabilisticStorage.get(registerIndex);
+              if(registerValue > currentRegisterValue) {
+                sparseProbabilisticStorage.put(registerIndex, registerValue);
+              }
             }
 
             // promotion, if necessary
             if(sparseProbabilisticStorage.size() > sparseThreshold) {
                 initializeStorage(HLLType.FULL);
-                for(final int registerIndex : sparseProbabilisticStorage.keySet()) {
-                    final byte registerValue = sparseProbabilisticStorage.get(registerIndex);
-                    probabilisticStorage.setMaxRegister(registerIndex, registerValue);
+                for(IntByteCursor c : sparseProbabilisticStorage) {
+                  final int registerIndex = c.key;
+                  final byte registerValue = c.value;
+                  probabilisticStorage.setMaxRegister(registerIndex, registerValue);
                 }
                 sparseProbabilisticStorage = null;
             }
@@ -887,7 +896,7 @@ public byte[] toBytes(final ISchemaVersion schemaVersion) {
                 final IWordSerializer serializer =
                     schemaVersion.getSerializer(type, Long.SIZE, explicitStorage.size());
 
-                final long[] values = explicitStorage.toLongArray();
+                final long[] values = explicitStorage.toArray();
                 Arrays.sort(values);
                 for(final long value : values) {
                     serializer.writeWord(value);
@@ -900,9 +909,10 @@ public byte[] toBytes(final ISchemaVersion schemaVersion) {
                 final IWordSerializer serializer =
                         schemaVersion.getSerializer(type, shortWordLength, sparseProbabilisticStorage.size());
 
-                final int[] indices = sparseProbabilisticStorage.keySet().toIntArray();
+                final int[] indices = sparseProbabilisticStorage.keys().toArray();
                 Arrays.sort(indices);
                 for(final int registerIndex : indices) {
+                    assert sparseProbabilisticStorage.containsKey(registerIndex);
                     final long registerValue = sparseProbabilisticStorage.get(registerIndex);
                     // pack index and value into "short word"
                     final long shortWord = ((registerIndex << regwidth) | registerValue);
diff --git a/src/main/java/net/agkn/hll/util/HLLUtil.java b/src/main/java/net/agkn/hll/util/HLLUtil.java
index d3f97f2..a45155d 100644
--- a/src/main/java/net/agkn/hll/util/HLLUtil.java
+++ b/src/main/java/net/agkn/hll/util/HLLUtil.java
@@ -59,7 +59,7 @@ public final class HLLUtil {
      *
      * @see #largeEstimator(int, int, double)
      * @see #largeEstimatorCutoff(int, int)
-     * @see <a href='http://research.neustar.biz/2013/01/24/hyperloglog-googles-take-on-engineering-hll/'>Blog post with section on 2^L</a>
+     * @see "<a href='http://research.neustar.biz/2013/01/24/hyperloglog-googles-take-on-engineering-hll/'>Blog post with section on 2^L</a>"
      */
     private static final double[] TWO_TO_L = new double[(HLL.MAXIMUM_REGWIDTH_PARAM + 1) * (HLL.MAXIMUM_LOG2M_PARAM + 1)];
 
@@ -178,7 +178,7 @@ public static double smallEstimator(final int m, final int numberOfZeroes) {
      * @param  registerSizeInBits the size of the HLL registers, in bits.
      * @return the cutoff for the large range correction.
      * @see #largeEstimator(int, int, double)
-     * @see <a href='http://research.neustar.biz/2013/01/24/hyperloglog-googles-take-on-engineering-hll/'>Blog post with section on 64 bit hashes and "large range correction" cutoff</a>
+     * @see "<a href='http://research.neustar.biz/2013/01/24/hyperloglog-googles-take-on-engineering-hll/'>Blog post with section on 64 bit hashes and 'large range correction' cutoff</a>"
      */
     public static double largeEstimatorCutoff(final int log2m, final int registerSizeInBits) {
         return (TWO_TO_L[(REG_WIDTH_INDEX_MULTIPLIER * registerSizeInBits) + log2m]) / 30.0;
@@ -193,7 +193,7 @@ public static double largeEstimatorCutoff(final int log2m, final int registerSiz
      * @param  registerSizeInBits the size of the HLL registers, in bits.
      * @param  estimator the original estimator ("E" in the paper).
      * @return a corrected cardinality estimate.
-     * @see <a href='http://research.neustar.biz/2013/01/24/hyperloglog-googles-take-on-engineering-hll/'>Blog post with section on 64 bit hashes and "large range correction"</a>
+     * @see "<a href='http://research.neustar.biz/2013/01/24/hyperloglog-googles-take-on-engineering-hll/'>Blog post with section on 64 bit hashes and 'large range correction'</a>"
      */
     public static double largeEstimator(final int log2m, final int registerSizeInBits, final double estimator) {
         final double twoToL = TWO_TO_L[(REG_WIDTH_INDEX_MULTIPLIER * registerSizeInBits) + log2m];
diff --git a/src/test/java/net/agkn/hll/ExplicitHLLTest.java b/src/test/java/net/agkn/hll/ExplicitHLLTest.java
index 80cf526..c942809 100644
--- a/src/test/java/net/agkn/hll/ExplicitHLLTest.java
+++ b/src/test/java/net/agkn/hll/ExplicitHLLTest.java
@@ -16,24 +16,22 @@
  * limitations under the License.
  */
 
-import static org.powermock.reflect.Whitebox.getInternalState;
-import static org.testng.Assert.assertEquals;
-import static org.testng.Assert.assertTrue;
-import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
+import org.junit.Test;
 
 import java.util.HashSet;
-import java.util.Random;
 
 import net.agkn.hll.serialization.ISchemaVersion;
 import net.agkn.hll.serialization.SerializationUtil;
-import org.testng.annotations.Test;
+
+import com.carrotsearch.hppc.LongHashSet;
+import com.carrotsearch.randomizedtesting.RandomizedTest;
 
 /**
  * Tests {@link HLL} of type {@link HLLType#EXPLICIT}.
  *
  * @author timon
  */
-public class ExplicitHLLTest {
+public class ExplicitHLLTest extends RandomizedTest {
     /**
      * Tests basic set semantics of {@link HLL#addRaw(long)}.
      */
@@ -180,11 +178,9 @@ public void randomValuesTest() {
         final HashSet<Long> canonical = new HashSet<Long>();
         final HLL hll = newHLL(explicitThreshold);
 
-        final long seed = 1L/*constant so results are reproducible*/;
-        final Random random = new Random(seed);
         for(int i=0;i<explicitThreshold;i++){
-            long randomLong = random.nextLong();
-            canonical.add(new Long(randomLong));
+            long randomLong = randomLong();
+            canonical.add(randomLong);
             hll.addRaw(randomLong);
         }
         final int canonicalCardinality = canonical.size();
@@ -222,8 +218,8 @@ public void promotionTest() {
      * Asserts that values in both sets are exactly equal.
      */
     private static void assertElementsEqual(final HLL hllA, final HLL hllB) {
-        final LongOpenHashSet internalSetA = (LongOpenHashSet)getInternalState(hllA, "explicitStorage");
-        final LongOpenHashSet internalSetB = (LongOpenHashSet)getInternalState(hllB, "explicitStorage");
+        final LongHashSet internalSetA = hllA.explicitStorage;
+        final LongHashSet internalSetB = hllB.explicitStorage;
 
         assertTrue(internalSetA.equals(internalSetB));
     }
diff --git a/src/test/java/net/agkn/hll/FullHLLTest.java b/src/test/java/net/agkn/hll/FullHLLTest.java
index e837929..ff32862 100644
--- a/src/test/java/net/agkn/hll/FullHLLTest.java
+++ b/src/test/java/net/agkn/hll/FullHLLTest.java
@@ -16,10 +16,8 @@
  * limitations under the License.
  */
 
-import static org.powermock.reflect.Whitebox.getInternalState;
-import static org.testng.Assert.assertEquals;
-import static org.testng.Assert.assertTrue;
-import static org.testng.Assert.assertFalse;
+import static org.junit.Assert.*;
+import org.junit.Test;
 
 import net.agkn.hll.serialization.ISchemaVersion;
 import net.agkn.hll.serialization.SerializationUtil;
@@ -27,8 +25,6 @@
 import net.agkn.hll.util.HLLUtil;
 import net.agkn.hll.util.LongIterator;
 
-import org.testng.annotations.Test;
-
 /**
  * Tests {@link HLL} of type {@link HLLType#FULL}.
  *
@@ -163,7 +159,7 @@ public void registerValueTest() {
         { // scoped locally for sanity
             final int regwidth = 4;
             final HLL hll = new HLL(log2m, regwidth, 128/*explicitThreshold, arbitrary, unused*/, 256/*sparseThreshold, arbitrary, unused*/, HLLType.FULL);
-            final BitVector bitVector = (BitVector)getInternalState(hll, "probabilisticStorage")/*for testing convenience*/;
+            final BitVector bitVector = hll.probabilisticStorage;
 
             // lower-bounds of the register
             hll.addRaw(0x000000000000001L/*'j'=1*/);
@@ -210,7 +206,7 @@ public void registerValueTest() {
         { // scoped locally for sanity
             final int regwidth = 5;
             final HLL hll = new HLL(log2m, regwidth, 128/*explicitThreshold, arbitrary, unused*/, 256/*sparseThreshold, arbitrary, unused*/, HLLType.FULL);
-            final BitVector bitVector = (BitVector)getInternalState(hll, "probabilisticStorage")/*for testing convenience*/;
+            final BitVector bitVector = hll.probabilisticStorage;
 
             // lower-bounds of the register
             hll.addRaw(0x0000000000000001L/*'j'=1*/);
@@ -256,7 +252,7 @@ public void clearTest() {
         final int m = 1 << log2m;
 
         final HLL hll = new HLL(log2m, regwidth, 128/*explicitThreshold, arbitrary, unused*/, 256/*sparseThreshold, arbitrary, unused*/, HLLType.FULL);
-        final BitVector bitVector = (BitVector)getInternalState(hll, "probabilisticStorage")/*for testing convenience*/;
+        final BitVector bitVector = hll.probabilisticStorage;
         for(int i=0; i<m; i++)
             bitVector.setRegister(i, i);
 
@@ -338,8 +334,8 @@ public void toFromBytesTest() {
      * Asserts that the two HLLs are register-wise equal.
      */
     private static void assertElementsEqual(final HLL hllA, final HLL hllB) {
-        final BitVector bitVectorA = (BitVector)getInternalState(hllA, "probabilisticStorage")/*for testing convenience*/;
-        final BitVector bitVectorB = (BitVector)getInternalState(hllA, "probabilisticStorage")/*for testing convenience*/;
+        final BitVector bitVectorA = hllA.probabilisticStorage;
+        final BitVector bitVectorB = hllB.probabilisticStorage;
 
         final LongIterator iterA = bitVectorA.registerIterator();
         final LongIterator iterB = bitVectorB.registerIterator();
diff --git a/src/test/java/net/agkn/hll/IntegrationTestGenerator.java b/src/test/java/net/agkn/hll/IntegrationTestGenerator.java
index 0c142d3..7490151 100644
--- a/src/test/java/net/agkn/hll/IntegrationTestGenerator.java
+++ b/src/test/java/net/agkn/hll/IntegrationTestGenerator.java
@@ -26,6 +26,7 @@
 import net.agkn.hll.serialization.SerializationUtil;
 import net.agkn.hll.util.NumberUtil;
 import static net.agkn.hll.ProbabilisticTestUtil.constructHLLValue;
+import static com.carrotsearch.randomizedtesting.RandomizedTest.*;
 
 /**
  * Generates test files for testing other implementations of HLL
@@ -37,8 +38,6 @@ public class IntegrationTestGenerator {
     // ************************************************************************
     // directory to output the generated tests
     private static final String OUTPUT_DIRECTORY = "/tmp/hll_test/";
-    // seed to make results reproducible
-    private static final long SEED = 1L;
 
     // ------------------------------------------------------------------------
     // configurations for HLLs, should mirror settings in PostgreSQL impl. tests
@@ -114,14 +113,12 @@ private static void fullCardinalityCorrectionTest(final ISchemaVersion schemaVer
     private static void globalStepTest(final ISchemaVersion schemaVersion) throws IOException {
         final FileWriter output = openOutput(schemaVersion, "comprehensive_promotion", TestType.ADD);
 
-        final Random random = new Random(SEED);
-
         // the accumulator, starts empty
         final HLL hll = newHLL(HLLType.EMPTY);
         initLineAdd(output, hll, schemaVersion);
 
         for(int i=0; i<10000/*arbitrary*/; i++) {
-            cumulativeAddLine(output, hll, random.nextLong(), schemaVersion);
+            cumulativeAddLine(output, hll, randomLong(), schemaVersion);
         }
 
         output.flush();
@@ -223,7 +220,7 @@ private static void sparseStepTest(final ISchemaVersion schemaVersion) throws IO
     private static void sparseRandomTest(final ISchemaVersion schemaVersion) throws IOException {
         final FileWriter output = openOutput(schemaVersion, "sparse_random", TestType.ADD);
 
-        final Random random = new Random(SEED);
+        final Random random = new Random(randomLong());
 
         // the accumulator, starts empty
         final HLL hll = newHLL(HLLType.SPARSE);
@@ -291,7 +288,7 @@ private static void sparseEdgeTest(final ISchemaVersion schemaVersion) throws IO
     private static void explicitPromotionTest(final ISchemaVersion schemaVersion) throws IOException {
         final FileWriter output = openOutput(schemaVersion, "explicit_promotion", TestType.UNION);
 
-        final Random random = new Random(SEED);
+        final Random random = new Random(randomLong());
 
         // the accumulator, starts empty
         final HLL hll = newHLL(HLLType.EMPTY);
@@ -324,7 +321,7 @@ private static void explicitPromotionTest(final ISchemaVersion schemaVersion) th
     private static void sparseProbabilisticPromotionTest(final ISchemaVersion schemaVersion) throws IOException {
         final FileWriter output = openOutput(schemaVersion, "sparse_promotion", TestType.UNION);
 
-        final Random random = new Random(SEED);
+        final Random random = new Random(randomLong());
 
         // the accumulator, starts empty
         final HLL hll = newHLL(HLLType.EMPTY);
@@ -361,7 +358,7 @@ private static void sparseProbabilisticPromotionTest(final ISchemaVersion schema
     private static void explicitOverlapTest(final ISchemaVersion schemaVersion) throws IOException {
         final FileWriter output = openOutput(schemaVersion, "explicit_explicit", TestType.UNION);
 
-        final Random random = new Random(SEED);
+        final Random random = new Random(randomLong());
 
         // the accumulator, starts empty
         final HLL hll = newHLL(HLLType.EMPTY);
@@ -396,7 +393,7 @@ private static void explicitOverlapTest(final ISchemaVersion schemaVersion) thro
     private static void sparseProbabilisticOverlapTest(final ISchemaVersion schemaVersion) throws IOException {
         final FileWriter output = openOutput(schemaVersion, "sparse_sparse", TestType.UNION);
 
-        final Random random = new Random(SEED);
+        final Random random = new Random(randomLong());
 
         // the accumulator, starts empty
         final HLL hll = newHLL(HLLType.EMPTY);
@@ -432,7 +429,7 @@ private static void sparseProbabilisticOverlapTest(final ISchemaVersion schemaVe
     private static void probabilisticUnionTest(final ISchemaVersion schemaVersion) throws IOException {
         final FileWriter output = openOutput(schemaVersion, "probabilistic_probabilistic", TestType.UNION);
 
-        final Random random = new Random(SEED);
+        final Random random = new Random(randomLong());
 
         // the accumulator, starts empty
         final HLL hll = newHLL(HLLType.EMPTY);
@@ -464,8 +461,6 @@ private static void probabilisticUnionTest(final ISchemaVersion schemaVersion) t
     private static void globalUnionTest(final ISchemaVersion schemaVersion) throws IOException {
         final FileWriter output = openOutput(schemaVersion, "comprehensive", TestType.UNION);
 
-        final Random random = new Random(SEED);
-
         // the accumulator, starts empty
         final HLL hll = newHLL(HLLType.EMPTY);
         final HLL emptyHLL = newHLL(HLLType.EMPTY);
@@ -473,7 +468,7 @@ private static void globalUnionTest(final ISchemaVersion schemaVersion) throws I
         cumulativeUnionLine(output, hll, emptyHLL, schemaVersion);
 
         for(int i=0; i<1000/*number of rows to generate*/; i++) {
-            final HLL randomHLL = generateRandomHLL(random);
+            final HLL randomHLL = generateRandomHLL();
             cumulativeUnionLine(output, hll, randomHLL, schemaVersion);
         }
 
@@ -548,8 +543,8 @@ private static String stringCardinality(final HLL hll) {
      *         the HLL. This cannot be <code>null</code>.
      * @return the populated HLL. This will never be <code>null</code>.
      */
-    public static HLL generateRandomHLL(final Random random) {
-        final int randomTypeInt = random.nextInt(HLLType.values().length);
+    public static HLL generateRandomHLL() {
+        final int randomTypeInt = randomIntBetween(0, HLLType.values().length - 1);
         final HLLType type;
         switch(randomTypeInt) {
             case 0:
@@ -595,10 +590,10 @@ public static HLL generateRandomHLL(final Random random) {
 
         final HLL hll = newHLL(HLLType.EMPTY);
         for(int i=0; i<cardinalityBaseline; i++) {
-            hll.addRaw(random.nextLong());
+            hll.addRaw(randomLong());
         }
-        for(int i=0; i<random.nextInt(cardinalityCap - cardinalityBaseline); i++) {
-            hll.addRaw(random.nextLong());
+        for(int i=0; i<randomInt(cardinalityCap - cardinalityBaseline); i++) {
+            hll.addRaw(randomLong());
         }
 
         return hll;
diff --git a/src/test/java/net/agkn/hll/SparseHLLTest.java b/src/test/java/net/agkn/hll/SparseHLLTest.java
index f02e481..d5198c8 100644
--- a/src/test/java/net/agkn/hll/SparseHLLTest.java
+++ b/src/test/java/net/agkn/hll/SparseHLLTest.java
@@ -16,24 +16,22 @@
  * limitations under the License.
  */
 
-import static org.powermock.reflect.Whitebox.getInternalState;
-import static org.testng.Assert.assertEquals;
-import static org.testng.Assert.assertTrue;
-import it.unimi.dsi.fastutil.ints.Int2ByteOpenHashMap;
-import java.util.Random;
+import org.junit.Test;
 
 import net.agkn.hll.serialization.ISchemaVersion;
 import net.agkn.hll.serialization.SerializationUtil;
 import net.agkn.hll.util.HLLUtil;
 
-import org.testng.annotations.Test;
+import com.carrotsearch.hppc.IntByteHashMap;
+import com.carrotsearch.hppc.cursors.IntByteCursor;
+import com.carrotsearch.randomizedtesting.RandomizedTest;
 
 /**
  * Tests {@link HLL} of type {@link HLLType#SPARSE}.
  *
  * @author timon
  */
-public class SparseHLLTest {
+public class SparseHLLTest extends RandomizedTest {
     private static final int log2m = 11;
 
     /**
@@ -396,17 +394,13 @@ public void randomValuesTest() {
         final int regwidth = 5/*arbitrary*/;
         final int sparseThreshold = 256/*arbitrary*/;
 
-        final long seed = 1L;
-        final Random random = new Random(seed);
-
         for(int run=0; run<100; run++) {
             final HLL hll = new HLL(log2m, regwidth, 128/*explicitThreshold, arbitrary, unused*/, sparseThreshold, HLLType.SPARSE);
 
-            final Int2ByteOpenHashMap map = new Int2ByteOpenHashMap();
-            map.defaultReturnValue((byte)0);
+            final IntByteHashMap map = new IntByteHashMap();
 
             for(int i=0; i<sparseThreshold; i++) {
-                final long rawValue = random.nextLong();
+                final long rawValue = randomLong();
 
                 final short registerIndex = ProbabilisticTestUtil.getRegisterIndex(rawValue, log2m);
                 final byte registerValue = ProbabilisticTestUtil.getRegisterValue(rawValue, log2m);
@@ -417,9 +411,9 @@ public void randomValuesTest() {
                 hll.addRaw(rawValue);
             }
 
-            for(int key : map.keySet()) {
-                final byte expectedRegisterValue = map.get(key);
-                assertRegisterPresent(hll, key, expectedRegisterValue);
+            for (IntByteCursor c : map) {
+                final byte expectedRegisterValue = map.get(c.key);
+                assertRegisterPresent(hll, c.key, expectedRegisterValue);
             }
         }
     }
@@ -433,7 +427,7 @@ public void randomValuesTest() {
     private static void assertRegisterPresent(final HLL hll,
                                               final int registerIndex,
                                               final int registerValue) {
-        final Int2ByteOpenHashMap sparseProbabilisticStorage = (Int2ByteOpenHashMap)getInternalState(hll, "sparseProbabilisticStorage");
+        final IntByteHashMap sparseProbabilisticStorage = hll.sparseProbabilisticStorage;
         assertEquals(sparseProbabilisticStorage.get(registerIndex), registerValue);
     }
 
@@ -443,7 +437,7 @@ private static void assertRegisterPresent(final HLL hll,
     private static void assertOneRegisterSet(final HLL hll,
                                              final int registerIndex,
                                              final byte registerValue) {
-        final Int2ByteOpenHashMap sparseProbabilisticStorage = (Int2ByteOpenHashMap)getInternalState(hll, "sparseProbabilisticStorage");
+        final IntByteHashMap sparseProbabilisticStorage = hll.sparseProbabilisticStorage;
         assertEquals(sparseProbabilisticStorage.size(), 1);
         assertEquals(sparseProbabilisticStorage.get(registerIndex), registerValue);
     }
@@ -452,11 +446,12 @@ private static void assertOneRegisterSet(final HLL hll,
      * Asserts that all registers in the two {@link HLL} instances are identical.
      */
     private static void assertElementsEqual(final HLL hllA, final HLL hllB) {
-        final Int2ByteOpenHashMap sparseProbabilisticStorageA = (Int2ByteOpenHashMap)getInternalState(hllA, "sparseProbabilisticStorage");
-        final Int2ByteOpenHashMap sparseProbabilisticStorageB = (Int2ByteOpenHashMap)getInternalState(hllB, "sparseProbabilisticStorage");
+        final IntByteHashMap sparseProbabilisticStorageA = hllA.sparseProbabilisticStorage;
+        final IntByteHashMap sparseProbabilisticStorageB = hllB.sparseProbabilisticStorage;
         assertEquals(sparseProbabilisticStorageA.size(), sparseProbabilisticStorageB.size());
-        for(final int index : sparseProbabilisticStorageA.keySet()) {
-            assertEquals(sparseProbabilisticStorageA.get(index), sparseProbabilisticStorageB.get(index));
+        for (IntByteCursor c : sparseProbabilisticStorageA) {
+            assertEquals(sparseProbabilisticStorageA.get(c.key), 
+                         sparseProbabilisticStorageB.get(c.key));
         }
     }
 }
diff --git a/src/test/java/net/agkn/hll/serialization/BigEndianAscendingWordDeserializerTest.java b/src/test/java/net/agkn/hll/serialization/BigEndianAscendingWordDeserializerTest.java
index b2701ae..1211904 100644
--- a/src/test/java/net/agkn/hll/serialization/BigEndianAscendingWordDeserializerTest.java
+++ b/src/test/java/net/agkn/hll/serialization/BigEndianAscendingWordDeserializerTest.java
@@ -17,23 +17,21 @@
  */
 
 
-import org.testng.annotations.Test;
 import java.util.Random;
 
-import static org.testng.Assert.assertEquals;
-import static org.testng.Assert.assertTrue;
-import static org.testng.Assert.fail;
+import org.junit.Test;
+
+import com.carrotsearch.randomizedtesting.RandomizedTest;
 
 /**
  * Unit and smoke tests for {@link BigEndianAscendingWordDeserializer}.
  *
  * @author timon
  */
-public class BigEndianAscendingWordDeserializerTest {
+public class BigEndianAscendingWordDeserializerTest extends RandomizedTest {
     /**
      * Error checking tests for constructor.
      */
-    @SuppressWarnings("unused")
     @Test
     public void constructorErrorTest() {
         // word length too small
@@ -110,7 +108,7 @@ public void ascendingSmokeTest() {
     @Test
     public void randomSmokeTest() {
         for(int wordLength=5; wordLength<65; wordLength++) {
-            runRandomTest(wordLength, 3/*bytePadding, arbitrary*/, 100000/*wordCount, arbitrary*/, (long)wordLength/*seed, arbitrary*/);
+            runRandomTest(wordLength, 3/*bytePadding, arbitrary*/, 100000/*wordCount, arbitrary*/);
         }
     }
 
@@ -123,7 +121,8 @@ public void randomSmokeTest() {
      * @param wordCount the number of word values to test
      * @param seed the seed to the random value generator
      */
-    private static void runRandomTest(final int wordLength, final int bytePadding, final int wordCount, final long seed) {
+    private static void runRandomTest(final int wordLength, final int bytePadding, final int wordCount) {
+        final long seed = randomLong();
         final Random random = new Random(seed);
         final Random verificationRandom = new Random(seed);
 
diff --git a/src/test/java/net/agkn/hll/serialization/BigEndianAscendingWordSerializerTest.java b/src/test/java/net/agkn/hll/serialization/BigEndianAscendingWordSerializerTest.java
index 45c9d0a..3042812 100644
--- a/src/test/java/net/agkn/hll/serialization/BigEndianAscendingWordSerializerTest.java
+++ b/src/test/java/net/agkn/hll/serialization/BigEndianAscendingWordSerializerTest.java
@@ -16,12 +16,10 @@
  * limitations under the License.
  */
 
-import static org.testng.Assert.assertTrue;
-import static org.testng.Assert.fail;
-
 import java.util.Arrays;
 
-import org.testng.annotations.Test;
+import static org.junit.Assert.*;
+import org.junit.Test;
 
 /**
  * Unit tests for {@link BigEndianAscendingWordSerializer}.
@@ -32,7 +30,6 @@ public class BigEndianAscendingWordSerializerTest {
     /**
      * Error checking tests for constructor.
      */
-    @SuppressWarnings("unused")
     @Test
     public void constructorErrorTest() {
         // word length too small
diff --git a/src/test/java/net/agkn/hll/serialization/HLLSerializationTest.java b/src/test/java/net/agkn/hll/serialization/HLLSerializationTest.java
index c3d0d94..bae68fe 100644
--- a/src/test/java/net/agkn/hll/serialization/HLLSerializationTest.java
+++ b/src/test/java/net/agkn/hll/serialization/HLLSerializationTest.java
@@ -2,9 +2,13 @@
 
 import net.agkn.hll.HLL;
 import net.agkn.hll.HLLType;
-import org.testng.annotations.Test;
+
+import org.junit.Test;
+
+import com.carrotsearch.randomizedtesting.RandomizedTest;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
 import java.util.Random;
@@ -14,7 +18,6 @@
 import static net.agkn.hll.HLL.MINIMUM_EXPTHRESH_PARAM;
 import static net.agkn.hll.HLL.MINIMUM_LOG2M_PARAM;
 import static net.agkn.hll.HLL.MINIMUM_REGWIDTH_PARAM;
-import static org.testng.Assert.assertEquals;
 
 /**
  * Serialization smoke-tests.
@@ -22,23 +25,19 @@
  * @author yerenkow
  * @author benl
  */
-public class HLLSerializationTest {
-    // A fixed random seed so that this test is reproducible.
-    private static final long RANDOM_SEED = 1L;
-
+public class HLLSerializationTest extends RandomizedTest {
     /**
      * A smoke-test that covers serialization/deserialization of an HLL
      * under all possible parameters.
      */
     @Test
     public void serializationSmokeTest() throws Exception {
-        final Random random = new Random(RANDOM_SEED);
+        final Random random = new Random(randomLong());
         final int randomCount = 250;
-        final List<Long> randoms = new ArrayList<Long>(randomCount){{
-            for (int i=0; i<randomCount; i++) {
-                add(random.nextLong());
-            }
-        }};
+        final List<Long> randoms = new ArrayList<Long>(randomCount);
+        for (int i=0; i<randomCount; i++) {
+          randoms.add(random.nextLong());
+      }
 
         assertCardinality(HLLType.EMPTY, randoms);
         assertCardinality(HLLType.EXPLICIT, randoms);
@@ -65,12 +64,12 @@ private static void assertCardinality(final HLLType hllType, final Collection<Lo
                         HLL copy = HLL.fromBytes(hll.toBytes());
                         assertEquals(copy.cardinality(), hll.cardinality());
                         assertEquals(copy.getType(), hll.getType());
-                        assertEquals(copy.toBytes(), hll.toBytes());
+                        assertTrue(Arrays.equals(copy.toBytes(), hll.toBytes()));
 
                         HLL clone = hll.clone();
                         assertEquals(clone.cardinality(), hll.cardinality());
                         assertEquals(clone.getType(), hll.getType());
-                        assertEquals(clone.toBytes(), hll.toBytes());
+                        assertTrue(Arrays.equals(clone.toBytes(), hll.toBytes()));
                     }
                 }
             }
diff --git a/src/test/java/net/agkn/hll/util/BitVectorTest.java b/src/test/java/net/agkn/hll/util/BitVectorTest.java
index 724030b..1c68bb5 100644
--- a/src/test/java/net/agkn/hll/util/BitVectorTest.java
+++ b/src/test/java/net/agkn/hll/util/BitVectorTest.java
@@ -16,11 +16,8 @@
  * limitations under the License.
  */
 
-import static org.testng.Assert.assertEquals;
-import static org.testng.Assert.assertFalse;
-import static org.testng.Assert.assertTrue;
-
-import org.testng.annotations.Test;
+import static org.junit.Assert.*;
+import org.junit.Test;
 
 /**
  * Unit tests for {@link BitVector}.
@@ -118,11 +115,11 @@ private static void assertIterator(final int width, final int count) {
         final LongIterator iter = vector.registerIterator();
 
         for(int i=0; i<count; i++) {
-            assertTrue(iter.hasNext(), String.format("expected more elements: width=%s, count=%s", width, count));
+            assertTrue(String.format("expected more elements: width=%s, count=%s", width, count), iter.hasNext());
             // TODO: fill with a sentinel value
             assertEquals(iter.next(), 0);
         }
-        assertFalse(iter.hasNext(), String.format("expected no more elements: width=%s, count=%s", width, count));
+        assertFalse(String.format("expected no more elements: width=%s, count=%s", width, count), iter.hasNext());
     }
 
     // ========================================================================
diff --git a/src/test/java/net/agkn/hll/util/HLLUtilTest.java b/src/test/java/net/agkn/hll/util/HLLUtilTest.java
index d2cc7db..fc654ac 100644
--- a/src/test/java/net/agkn/hll/util/HLLUtilTest.java
+++ b/src/test/java/net/agkn/hll/util/HLLUtilTest.java
@@ -16,10 +16,10 @@
  * limitations under the License.
  */
 
-import static org.testng.Assert.assertEquals;
 import net.agkn.hll.HLL;
 
-import org.testng.annotations.Test;
+import static org.junit.Assert.*;
+import org.junit.Test;
 
 /**
  * Tests {@link HLLUtil} static methods.
@@ -41,7 +41,7 @@ public void largeEstimatorCutoffTest() {
                 // and original paper (Fig. 3) for information on 2^L and
                 // "large range correction" cutoff.
                 final double expected = Math.pow(2, Math.pow(2, regWidth) - 2 + log2m) / 30.0;
-                assertEquals(cutoff, expected);
+                assertEquals(cutoff, expected, 0.0001);
             }
         }
     }