diff --git a/contrib/kiss-chroot b/contrib/kiss-chroot
index e391a11..86212db 100755
--- a/contrib/kiss-chroot
+++ b/contrib/kiss-chroot
@@ -48,8 +48,8 @@ main() {
             SHELL=/bin/sh \
             USER=root \
             KISS_ASROOT=1 \
-            CFLAGS="-march=${2:-x86-64} -mtune=generic -pipe -Os" \
-            CXXFLAGS="-march=${2:-x86-64} -mtune=generic -pipe -Os" \
+            CFLAGS="${2:--march=x86-64 -mtune=generic -pipe -Os}" \
+            CXXFLAGS="${2:---march=x86-64 -mtune=generic -pipe -Os}" \
             MAKEFLAGS="-j$(nproc 2>/dev/null || echo 1)" \
             /bin/sh -l
     }