diff --git a/tools/testing/ktest/ktest.pl b/tools/testing/ktest/ktest.pl
index 60fe020..89c2257 100755
--- a/tools/testing/ktest/ktest.pl
+++ b/tools/testing/ktest/ktest.pl
@@ -3571,7 +3571,9 @@
     undef %configs;
     assign_configs \%configs, $output_config;
 
-    return $config if (!defined($configs{$config}));
+    if (!defined($configs{$config}) || $configs{$config} =~ /^#/) {
+	return $config;
+    }
 
     doprint "disabling config $config did not change .config\n";