diff --git a/GNUmakefile b/GNUmakefile
index c582d84e..d40076a6 100755
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -190,7 +190,7 @@ endif # _WIN32_WINNT
 endif # IS_MINGW
 
 # For feature tests
-BAD_RESULT="fatal|error|unknown|unrecognized|illegal|ignored|incorrect|not found|not exist|cannot find|not supported|no such instruction"
+BAD_RESULT="fatal|error|unknown|unrecognized|illegal|ignored|incorrect|not found|not exist|cannot find|not supported|no such instruction|invalid mnemonic"
 
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 #####               X86/X32/X64 Options               #####