diff --git a/src/ruby/grpc.gemspec b/src/ruby/grpc.gemspec
index f615945b797..9d95db545f1 100755
--- a/src/ruby/grpc.gemspec
+++ b/src/ruby/grpc.gemspec
@@ -1,3 +1,4 @@
+# -*- ruby -*-
 # encoding: utf-8
 $LOAD_PATH.push File.expand_path('../lib', __FILE__)
 require 'grpc/version'