diff --git a/programs/util.c b/programs/util.c
index c93382c6..9afb5a86 100644
--- a/programs/util.c
+++ b/programs/util.c
@@ -326,11 +326,6 @@ int UTIL_prepareFileList(const char *dirName, char** bufStart, size_t* pos, char
 
 #endif /* #ifdef _WIN32 */
 
-/* Check if the file is Compressed by comparing it with compressFileExtension list.
-YES => Skip the file (return 1)
-NO => return 0
-*/
-
 int UTIL_isCompressedFile(const char *inputName, const char *extensionList[])
 {
   const char* ext = UTIL_getFileExtension(inputName);
@@ -338,8 +333,8 @@ int UTIL_isCompressedFile(const char *inputName, const char *extensionList[])
   {
      while(*extensionList!=NULL)
      {
-       const char* isCompressedExtension = strstr(ext,*extensionList);
-       if(isCompressedExtension)
+       const int isCompressedExtension = strcmp(ext,*extensionList);
+       if(isCompressedExtension==0)
           return 1;
         ++extensionList;
      }
diff --git a/tests/playTests.sh b/tests/playTests.sh
index 6161983e..4672ecaa 100755
--- a/tests/playTests.sh
+++ b/tests/playTests.sh
@@ -225,8 +225,8 @@ sleep 5
 ./datagen $size > precompressedFilterTestDir/input.7
 ./datagen $size > precompressedFilterTestDir/input.8
 $ZSTD --exclude-compressed --long --rm -r precompressedFilterTestDir
-test ! -f input.5.zst.zst
-test ! -f input.6.zst.zst
+test ! -f precompressedFilterTestDir/input.5.zst.zst
+test ! -f precompressedFilterTestDir/input.6.zst.zst
 file1timestamp=`date -r precompressedFilterTestDir/input.5.zst +%s`
 file2timestamp=`date -r precompressedFilterTestDir/input.7.zst +%s`
 if [[ $file2timestamp -ge $file1timestamp ]]; then
@@ -234,6 +234,16 @@ if [[ $file2timestamp -ge $file1timestamp ]]; then
 else
   println "Test is not successful"
 fi
+#File Extension check.
+./datagen $size > precompressedFilterTestDir/input.zstbar
+$ZSTD --exclude-compressed --long --rm -r precompressedFilterTestDir
+#ZSTD should compress input.zstbar
+test -f precompressedFilterTestDir/input.zstbar.zst
+#Check without the --exclude-compressed flag
+$ZSTD --long --rm -r precompressedFilterTestDir
+#Files should get compressed again without the --exclude-compressed flag.
+test -f precompressedFilterTestDir/input.5.zst.zst
+test -f precompressedFilterTestDir/input.6.zst.zst
 println "Test completed"
 
 println "test : file removal"