diff --git a/lib/src/voip/call_session.dart b/lib/src/voip/call_session.dart
index becb7b721..9f2fb0999 100644
--- a/lib/src/voip/call_session.dart
+++ b/lib/src/voip/call_session.dart
@@ -397,7 +397,12 @@ class CallSession {
     if (direction == CallDirection.kOutgoing) {
       setCallState(CallState.kConnecting);
       await pc!.setRemoteDescription(answer);
-      for (final candidate in _remoteCandidates) {
+
+      // Copy the list before iterating because `await` can yield execution,
+      // allowing `_remoteCandidates` to be modified elsewhere,
+      // which would cause a concurrent modification error
+      final candidates = List.of(_remoteCandidates);
+      for (final candidate in candidates) {
         await pc!.addCandidate(candidate);
       }
     }
diff --git a/lib/src/voip/models/call_events.dart b/lib/src/voip/models/call_events.dart
index ffa298c9e..08226096f 100644
--- a/lib/src/voip/models/call_events.dart
+++ b/lib/src/voip/models/call_events.dart
@@ -70,7 +70,7 @@ class CallReplaces {
 }
 
 // TODO: Change to "sdp_stream_metadata" when MSC3077 is merged
-const String sdpStreamMetadataKey = 'org.matrix.msc3077.sdp_stream_metadata';
+const String sdpStreamMetadataKey = 'sdp_stream_metadata';
 
 /// https://github.com/matrix-org/matrix-doc/blob/dbkr/msc2747/proposals/2747-voip-call-transfer.md#capability-advertisment
 /// https://github.com/matrix-org/matrix-doc/blob/dbkr/msc2746/proposals/2746-reliable-voip.md#add-dtmf