diff --git a/include/lib.sh b/include/lib.sh
index c5790bf7..abf4de3b 100644
--- a/include/lib.sh
+++ b/include/lib.sh
@@ -169,6 +169,7 @@ find_ex()
 
 x_()
 {
+	[ $# -lt 1 ] || [ -n "$1" ] || $err "Empty first arg: x_ $(echo "$@")"
 	[ $# -lt 1 ] || "$@" || $err "Unhandled error for: $(echo "$@")"; :
 }