diff --git a/packages/grpc-js/src/deadline-filter.ts b/packages/grpc-js/src/deadline-filter.ts
index b5e4cabc..190d815e 100644
--- a/packages/grpc-js/src/deadline-filter.ts
+++ b/packages/grpc-js/src/deadline-filter.ts
@@ -66,7 +66,7 @@ export class DeadlineFilter extends BaseFilter implements Filter {
           'Deadline exceeded'
         );
       }, timeout);
-      this.timer.unref();
+      this.timer.unref?.();
     }
   }