diff --git a/packages/rsocket-core/src/RSocketMachine.js b/packages/rsocket-core/src/RSocketMachine.js
index ae545bcc..02bbb3cc 100644
--- a/packages/rsocket-core/src/RSocketMachine.js
+++ b/packages/rsocket-core/src/RSocketMachine.js
@@ -888,7 +888,8 @@ class RSocketMachineImpl<D, M> implements RSocketMachine<D, M> {
       flags |= FLAGS.COMPLETE;
       this._subscriptions.delete(streamId);
     }
-    if (payload.metadata !== undefined) {
+    if (payload.metadata !== undefined &&
+        payload.metadata !== null) {
       // eslint-disable-next-line no-bitwise
       flags |= FLAGS.METADATA;
     }