diff -ru /cvs/sys_old/dev/musycc/musycc.c /usr/src/sys/dev/musycc/musycc.c
--- /cvs/sys_old/dev/musycc/musycc.c	Sun Dec 24 16:00:48 2000
+++ /usr/src/sys/dev/musycc/musycc.c	Sun Dec 24 20:09:33 2000
@@ -1208,7 +1208,35 @@
 		sc->mdt[ch][i].data = 0;
 
 		MGETHDR(m, M_TRYWAIT, MT_DATA);
+		if (m == NULL) {
+			/* We've waited mbuf_wait and still got nothing. */
+			/* We're calling with M_TRYWAIT anyway - a little
+			   defensive programming costs us very little - if
+			   almost nothing. */
+			while (i > 0) {
+				/* Don't leak all the previously allocated
+				   mbufs in this loop. */
+				i--;
+				m_free(sc->mdr[ch][i].m);
+			}
+			FREE(sc->mdt[ch], M_MUSYCC);
+			FREE(sc->mdr[ch], M_MUSYCC);
+			return ENOBUFS;
+		}
 		MCLGET(m, M_TRYWAIT);
+		if ((m->m_ext & M_EXT) == 0) {
+			/* We've waited mbuf_wait and still got nothing. */
+			while (i > 0) {
+				/* Don't leak all the previously allocated
+				   mbufs in this loop. */
+				i--;
+				m_free(sc->mdr[ch][i].m);
+			}
+			FREE(sc->mdt[ch], M_MUSYCC);
+			FREE(sc->mdr[ch], M_MUSYCC);
+			m_free(m);
+			return ENOBUFS;
+		}
 		sc->mdr[ch][i].m = m;
 		sc->mdr[ch][i].data = vtophys(m->m_data);
 		sc->mdr[ch][i].status = 1600; /* MTU */