diff --git a/spec/ruby/default.mspec b/spec/ruby/default.mspec
index a0dc69c03d..1e8f8893aa 100644
--- a/spec/ruby/default.mspec
+++ b/spec/ruby/default.mspec
@@ -1,3 +1,4 @@
+# -*- ruby -*-
 # Configuration file for Ruby >= 2.0 implementations.
 
 class MSpecScript