1 files changed, 3 insertions, 1 deletions

diff --git a/src/util/mq.c b/src/util/mq.c
index 0f9ad9a12..dbcce704d 100644
--- a/src/util/mq.c
+++ b/src/util/mq.c
@@ -780,7 +780,9 @@ GNUNET_MQ_notify_sent (struct GNUNET_MQ_Envelope *ev,
                        GNUNET_SCHEDULER_TaskCallback cb,
                        void *cb_cls)
 {
-  GNUNET_assert (NULL == ev->sent_cb);
+  /* allow setting *OR* clearing callback */
+  GNUNET_assert ( (NULL == ev->sent_cb) ||
+                  (NULL == cb) );
   ev->sent_cb = cb;
   ev->sent_cls = cb_cls;
 }