diff --git a/configure.ac b/configure.ac
index 4fa3a658..bb79853d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -194,7 +194,7 @@ case $host in
     ;;
        *)
     echo "Unknown CANONICAL_HOST $host"
-    exit
+    exit 1
     ;;
 esac