diff --git a/tools/make-firefox.sh b/tools/make-firefox.sh
index f32205b..d52a3a8 100755
--- a/tools/make-firefox.sh
+++ b/tools/make-firefox.sh
@@ -5,7 +5,7 @@
 echo "*** uBlock.firefox: Copying files"
 
 DES=dist/build/uBlock.firefox
-rm -r $DES
+rm -rf $DES
 mkdir -p $DES
 
 cp -R assets $DES/