diff --git a/lib/net/sftp/operations/file.rb b/lib/net/sftp/operations/file.rb
index d031050..85b1792 100644
--- a/lib/net/sftp/operations/file.rb
+++ b/lib/net/sftp/operations/file.rb
@@ -92,6 +92,7 @@ def gets(sep_or_limit=$/, limit=Float::INFINITY)
         sep_string = sep_or_limit
         lim = limit
       end
+      lim = Float::INFINITY if lim.nil? || lim < 0
 
       delim = if sep_string && sep_string.length == 0
         "#{$/}#{$/}"