diff --git a/mockgen/reflect.go b/mockgen/reflect.go
index 8f519f6..ca80ebb 100644
--- a/mockgen/reflect.go
+++ b/mockgen/reflect.go
@@ -187,6 +187,7 @@ type reflectData struct {
 // gob encoding of a model.Package to standard output.
 // JSON doesn't work because of the model.Type interface.
 var reflectProgram = template.Must(template.New("program").Parse(`
+// Code generated by MockGen. DO NOT EDIT.
 package main
 
 import (