diff --git a/electron.makefile b/electron.makefile
index a42f84f..626c7c4 100644
--- a/electron.makefile
+++ b/electron.makefile
@@ -13,8 +13,8 @@ copylocal:
 
 # modify index.html to use local files
 uselocal: copylocal
-	sed -i .bak 's,https://cdnjs.cloudflare.com/ajax/libs/[^\"]*/,3rdparty/,g' index.html
-	sed -i .bak 's, integrity=\".*\" crossorigin=\"anonymous\",,' index.html
+	sed -i.bak 's,https://cdnjs.cloudflare.com/ajax/libs/[^\"]*/,3rdparty/,g' index.html
+	sed -i.bak 's, integrity=\".*\" crossorigin=\"anonymous\",,' index.html
 
 # build the electron app for various platforms
 build-electron-windows: uselocal