diff --git a/src/crypto/olmlib.js b/src/crypto/olmlib.js
index a7dc7f7d2..7dcdda750 100644
--- a/src/crypto/olmlib.js
+++ b/src/crypto/olmlib.js
@@ -413,7 +413,7 @@ export function encodeBase64(uint8Array) {
  * @return {string} The unpadded base64.
  */
 export function encodeUnpaddedBase64(uint8Array) {
-    return encodeBase64(uint8Array).replace(/=$/g, '');
+    return encodeBase64(uint8Array).replace(/=+$/g, '');
 }
 
 /**