diff --git a/sys/netinet/in_mcast.c b/sys/netinet/in_mcast.c
--- a/sys/netinet/in_mcast.c
+++ b/sys/netinet/in_mcast.c
@@ -915,8 +915,6 @@
 	imf->imf_st[0] = imf->imf_st[1] = MCAST_UNDEFINED;
 	KASSERT(RB_EMPTY(&imf->imf_sources),
 	    ("%s: imf_sources not empty", __func__));
-	if (imf->imf_inm != NULL)
-		mbufq_drain(&imf->imf_inm->inm_scq);
 }
 
 /*
@@ -1183,6 +1181,7 @@
 		free(ims, M_IPMSOURCE);
 		inm->inm_nsrc--;
 	}
+	mbufq_drain(&inm->inm_scq);
 }
 
 /*