diff --git a/src/snapshot.ts b/src/snapshot.ts
index 2c0f67e4..c01f5b2c 100644
--- a/src/snapshot.ts
+++ b/src/snapshot.ts
@@ -10,7 +10,7 @@ import {
 } from './types';
 
 let _id = 1;
-const tagNameRegex = RegExp('[^a-z1-6-_]');
+const tagNameRegex = RegExp('[^a-z0-9-_]');
 
 export const IGNORED_NODE = -2;