diff --git a/src/crypto/algorithms/base.js b/src/crypto/algorithms/base.js
index bcf536fa2..685332085 100644
--- a/src/crypto/algorithms/base.js
+++ b/src/crypto/algorithms/base.js
@@ -169,7 +169,7 @@ utils.inherits(DecryptionError, Error);
  * @returns {String}
  */
 DecryptionError.prototype.toString = function() {
-    let result = this.name + '[msg: '+ this.message;
+    let result = this.name + '[msg: ' + this.message;
 
     if (this.details) {
         result += ', ' +
diff --git a/src/crypto/algorithms/megolm.js b/src/crypto/algorithms/megolm.js
index f3a76eb1b..f7d7b770e 100644
--- a/src/crypto/algorithms/megolm.js
+++ b/src/crypto/algorithms/megolm.js
@@ -606,10 +606,13 @@ MegolmDecryption.prototype.onRoomKeyEvent = function(event) {
 
     if (!content.room_id ||
         !sessionId ||
-        !content.session_key ||
-        !senderKey
+        !content.session_key
        ) {
-        console.error(`key event is missing fields`);
+        console.error("key event is missing fields");
+        return;
+    }
+    if (!senderKey) {
+        console.error("key event has no sender key (not encrypted?)");
         return;
     }