diff --git a/lib/Test/Class.pm b/lib/Test/Class.pm
index 7b6c899..70d9e74 100644
--- a/lib/Test/Class.pm
+++ b/lib/Test/Class.pm
@@ -342,7 +342,7 @@ sub _isa_class {
 
 sub _test_classes {
     my $class = shift;
-    return( @{mro::get_isarev($class)}, $class );
+    return( sort @{mro::get_isarev($class)}, $class );
 };
 
 sub runtests {