diff --git a/src/components/views/rooms/MessageComposerButtons.tsx b/src/components/views/rooms/MessageComposerButtons.tsx
index e659fb069f..20c8d05466 100644
--- a/src/components/views/rooms/MessageComposerButtons.tsx
+++ b/src/components/views/rooms/MessageComposerButtons.tsx
@@ -321,7 +321,7 @@ class PollButton extends React.PureComponent<IPollButtonProps> {
                 },
             );
         } else {
-            const threadId = this.props.relation.rel_type === RelationType.Thread
+            const threadId = this.props.relation?.rel_type === RelationType.Thread
                 ? this.props.relation.event_id
                 : null;