diff --git a/lib/linguist/languages.yml b/lib/linguist/languages.yml
index 1f65e5ea..9ff464d2 100644
--- a/lib/linguist/languages.yml
+++ b/lib/linguist/languages.yml
@@ -1091,7 +1091,6 @@ Prolog:
 
 Protocol Buffer:
   type: markup
-  ace_mode: protobuf
   aliases:
   - protobuf
   - Protocol Buffers