diff --git a/vexflow/vexflow.d.ts b/vexflow/vexflow.d.ts
index 1cc54fa8a..c17c4f710 100644
--- a/vexflow/vexflow.d.ts
+++ b/vexflow/vexflow.d.ts
@@ -1351,7 +1351,7 @@ declare module Vex {
         }
         
         export module Volta {
-            enum type {NONE, BEGIN, MID, END, BEGIN_END}
+            const enum type {NONE, BEGIN, MID, END, BEGIN_END}
         }
         
         class Volta extends StaveModifier {