diff --git a/scripts/mkmakefile b/scripts/mkmakefile
index a22cbed..7f9d544 100644
--- a/scripts/mkmakefile
+++ b/scripts/mkmakefile
@@ -10,7 +10,10 @@
 # $4 - patchlevel
 
 
-cat << EOF
+test ! -r $2/Makefile -o -O $2/Makefile || exit 0
+echo "  GEN     $2/Makefile"
+
+cat << EOF > $2/Makefile
 # Automatically generated by $0: don't edit
 
 VERSION = $3