diff --git a/tools/test_modules/m00000.pm b/tools/test_modules/m00000.pm
index 3016c4a96..8574ee74a 100644
--- a/tools/test_modules/m00000.pm
+++ b/tools/test_modules/m00000.pm
@@ -32,6 +32,8 @@ sub module_verify_hash
 
   my $new_hash = module_generate_hash ($word);
 
+  return unless defined $new_hash;
+
   return unless $new_hash eq $hash;
 
   return $new_hash;
diff --git a/tools/test_modules/m00100.pm b/tools/test_modules/m00100.pm
index cfa422e91..7c750f937 100644
--- a/tools/test_modules/m00100.pm
+++ b/tools/test_modules/m00100.pm
@@ -32,6 +32,8 @@ sub module_verify_hash
 
   my $new_hash = module_generate_hash ($word);
 
+  return unless defined $new_hash;
+
   return unless $new_hash eq $hash;
 
   return $new_hash;
diff --git a/tools/test_modules/m00110.pm b/tools/test_modules/m00110.pm
index 5c8e8f9c4..a1f1138ef 100644
--- a/tools/test_modules/m00110.pm
+++ b/tools/test_modules/m00110.pm
@@ -34,6 +34,8 @@ sub module_verify_hash
 
   my $new_hash = module_generate_hash ($word, $salt);
 
+  return unless defined $new_hash;
+
   return unless $new_hash eq "$hash:$salt";
 
   return $new_hash;
diff --git a/tools/test_modules/m00120.pm b/tools/test_modules/m00120.pm
index 71325a2d4..2f536f1f4 100644
--- a/tools/test_modules/m00120.pm
+++ b/tools/test_modules/m00120.pm
@@ -34,6 +34,8 @@ sub module_verify_hash
 
   my $new_hash = module_generate_hash ($word, $salt);
 
+  return unless defined $new_hash;
+
   return unless $new_hash eq "$hash:$salt";
 
   return $new_hash;
diff --git a/tools/test_modules/m18400.pm b/tools/test_modules/m18400.pm
index 182e5bb61..0391866b8 100644
--- a/tools/test_modules/m18400.pm
+++ b/tools/test_modules/m18400.pm
@@ -102,6 +102,8 @@ sub module_verify_hash
 
   my $new_hash = module_generate_hash ($word, $salt, $iter, $iv, $plain);
 
+  return unless defined $new_hash;
+
   return unless $new_hash eq $hash;
 
   return $new_hash;
diff --git a/tools/test_modules/m18600.pm b/tools/test_modules/m18600.pm
index 68155ad96..2b3e307db 100644
--- a/tools/test_modules/m18600.pm
+++ b/tools/test_modules/m18600.pm
@@ -128,6 +128,8 @@ sub module_verify_hash
 
   my $new_hash = module_generate_hash ($word, $salt, $iter, $iv, $plain);
 
+  return unless defined $new_hash;
+
   return unless $new_hash eq $hash;
 
   return $new_hash;