diff --git a/test/asm/test.sh b/test/asm/test.sh
index 80b0ff41..6d13fc54 100755
--- a/test/asm/test.sh
+++ b/test/asm/test.sh
@@ -62,10 +62,10 @@ fi
 # Check whether to use '.simple.err' files if they exist
 # (rgbasm with pre-3.0 Bison just reports "syntax error")
 $RGBASM -Weverything -o $o syntax-error.asm > $output 2> $errput
-cmp syntax-error.err $errput > /dev/null 2> /dev/null
-simple_error=$?
-if [ "$simple_error" -eq 1 ]; then
+simple_error=0
+if ! diff --strip-trailing-cr syntax-error.err $errput; then
 	echo "${bold}${orange}Warning: using .simple.err files when available.${rescolors}${resbold}"
+	simple_error=1
 fi
 
 for i in *.asm; do