diff --git a/pkg/mumbleproto/sync.bash b/pkg/mumbleproto/sync.bash
index 04257b0..42a2745 100755
--- a/pkg/mumbleproto/sync.bash
+++ b/pkg/mumbleproto/sync.bash
@@ -2,4 +2,4 @@
 # Syncs the Mumble.proto file with the main Mumble repo
 
 curl -O https://raw.github.com/mumble-voip/mumble/master/src/Mumble.proto
-sed -i -e 's,MumbleProto,mumbleproto,' Mumble.proto
+sed -i '' -e 's,MumbleProto,mumbleproto,' Mumble.proto