diff --git a/config.guess b/config.guess
index 7d507bb..dc0a6b2 100755
--- a/config.guess
+++ b/config.guess
@@ -1437,10 +1437,9 @@ EOF
 	# "uname -m" is not consistent, so use $cputype instead. 386
 	# is converted to i386 for consistency with other x86
 	# operating systems.
-	# shellcheck disable=SC2154
-	if test "$cputype" = 386; then
+	if test "${cputype-}" = 386; then
 	    UNAME_MACHINE=i386
-	else
+	elif test "x${cputype-}" != x; then
 	    UNAME_MACHINE="$cputype"
 	fi
 	echo "$UNAME_MACHINE"-unknown-plan9