diff --git a/packages/sysutils/busybox/build b/packages/sysutils/busybox/build
index a539cd5966..1e1b99b9df 100755
--- a/packages/sysutils/busybox/build
+++ b/packages/sysutils/busybox/build
@@ -9,7 +9,7 @@ else
 fi
 
 # optimize for size
-  CFLAGS=`echo $CFLAGS | sed -e "s|-O?|-Os|"`
+  CFLAGS=`echo $CFLAGS | sed -e "s|-O.|-Os|"`
 
 LDFLAGS="$LDFLAGS -fwhole-program"