diff --git a/lib/crypto/algorithms/megolm.js b/lib/crypto/algorithms/megolm.js
index 7e87ad37c..1444f3b5e 100644
--- a/lib/crypto/algorithms/megolm.js
+++ b/lib/crypto/algorithms/megolm.js
@@ -501,7 +501,7 @@ MegolmDecryption.prototype.decryptEvent = function(event) {
         );
     }
 
-    event.setClearData(payload, res.keysClaimed, res.keysProved);
+    event.setClearData(payload, res.keysProved, res.keysClaimed);
 };