diff --git a/lib/consumer.js b/lib/consumer.js
index d85a7351..3e00d5fa 100644
--- a/lib/consumer.js
+++ b/lib/consumer.js
@@ -158,7 +158,7 @@ function autoCommit (force, cb) {
     force = false;
   }
 
-  if (this.committing && !force) return cb(null, 'Offset committing');
+  if (this.committing && !force && cb) return cb(null, 'Offset committing');
 
   this.committing = true;
   setTimeout(function () {