diff --git a/Zend/tests/class_alias/gh16665_3.phpt b/Zend/tests/class_alias/gh16665_3.phpt
new file mode 100644
index 0000000000000..038ab398dffb0
--- /dev/null
+++ b/Zend/tests/class_alias/gh16665_3.phpt
@@ -0,0 +1,8 @@
+--TEST--
+GH-16665 (\resource should not be usable)
+--FILE--
+<?php
+class_alias('stdClass', 'resource');
+?>
+--EXPECTF--
+Fatal error: Cannot use "resource" as a class alias as it is reserved in %s on line %d
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index 5eba2ec1366fa..bee25b6e6ea92 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -215,6 +215,7 @@ static const struct reserved_class_name reserved_class_names[] = {
 	{ZEND_STRL("iterable")},
 	{ZEND_STRL("object")},
 	{ZEND_STRL("mixed")},
+	{ZEND_STRL("resource")},
 	/* These are not usable as class names because they're proper tokens,
 	 * but they are here for class aliases. */
 	{ZEND_STRL("array")},