diff --git a/libosmocore/src/msgb.c b/libosmocore/src/msgb.c
index 9117a0a..a60e2ff 100644
--- a/libosmocore/src/msgb.c
+++ b/libosmocore/src/msgb.c
@@ -85,4 +85,6 @@
 	msg->l2h = NULL;
 	msg->l3h = NULL;
 	msg->l4h = NULL;
+
+	memset(&msg->cb, 0, sizeof(msg->cb));
 }