diff --git a/lib/isccc/ccmsg.c b/lib/isccc/ccmsg.c
index 4c033dd975..4c5ff61e5f 100644
--- a/lib/isccc/ccmsg.c
+++ b/lib/isccc/ccmsg.c
@@ -150,11 +150,13 @@ ccmsg_senddone(isc_nmhandle_t *handle, isc_result_t eresult, void *arg) {
 	isccc_ccmsg_t *ccmsg = arg;
 
 	REQUIRE(VALID_CCMSG(ccmsg));
+	REQUIRE(ccmsg->send_cb != NULL);
 
-	INSIST(ccmsg->send_cb != NULL);
-	ccmsg->send_cb(handle, eresult, ccmsg->send_cbarg);
+	isc_nm_cb_t send_cb = ccmsg->send_cb;
 	ccmsg->send_cb = NULL;
 
+	send_cb(handle, eresult, ccmsg->send_cbarg);
+
 	isc_nmhandle_detach(&handle);
 }