diff --git a/packages/sysutils/busybox/build b/packages/sysutils/busybox/build
index a6c36c70e2..79dc1e30ae 100755
--- a/packages/sysutils/busybox/build
+++ b/packages/sysutils/busybox/build
@@ -29,6 +29,7 @@ else
 fi
 
 # optimize for size
+  CFLAGS=`echo $CFLAGS | sed -e "s|-Ofast|-Os|"`
   CFLAGS=`echo $CFLAGS | sed -e "s|-O.|-Os|"`
 
 LDFLAGS="$LDFLAGS -fwhole-program"