diff --git a/js/lz-string.ts b/js/lz-string.ts
index fb468b9..fea9936 100644
--- a/js/lz-string.ts
+++ b/js/lz-string.ts
@@ -14,6 +14,8 @@
 const f = String.fromCharCode;
 const keyStrUriSafe =
   'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-!';
+export const keyStrBase64Safe =
+  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
 const baseReverseDic: Record<string, { [key: string]: number }> = {};
 
 /**