diff --git a/sys/dev/pci/if_iwx.c b/sys/dev/pci/if_iwx.c
index 580b5e3dd780..0c666f51747b 100644
--- a/sys/dev/pci/if_iwx.c
+++ b/sys/dev/pci/if_iwx.c
@@ -6197,7 +6197,7 @@ iwx_send_cmd(struct iwx_softc *sc, struct iwx_host_cmd *hcmd)
 			goto out;
 		}
 		MCLAIM(m, &sc->sc_ec.ec_tx_mowner);
-		MEXTMALLOC(m, totlen, M_DONTWAIT);
+		MEXTMALLOC(m, totlen + 64, M_DONTWAIT);
 		if (!(m->m_flags & M_EXT)) {
 			printf("%s: could not get fw cmd mbuf (%zd bytes)\n",
 			    DEVNAME(sc), totlen);
@@ -6205,6 +6205,8 @@ iwx_send_cmd(struct iwx_softc *sc, struct iwx_host_cmd *hcmd)
 			goto out;
 		}
 		cmd = mtod(m, struct iwx_device_cmd *);
+		printf("%s:%d: m=%p dataptr=%p\n", __func__, __LINE__, m, cmd);
+		memset(cmd, 0, totlen + 64);
 		err = bus_dmamap_load(sc->sc_dmat, txdata->map, cmd,
 		    totlen, NULL, BUS_DMA_NOWAIT | BUS_DMA_WRITE);
 		if (err) {
@@ -6397,6 +6399,12 @@ iwx_cmd_done(struct iwx_softc *sc, int qid, int idx, int code)
 	data = &ring->data[idx];
 
 	if (data->m != NULL) {
+		const void *ptr = mtod(m, void *);
+		printf("%s:%d: m=%p dataptr=%p\n", __func__, __LINE__, m, ptr);
+		if (m->m_flags & M_EXT)
+			hexdump(printf, "ext", ptr, m->m_ext.ext_size);
+		else
+			hexdump(printf, "no ext", ptr, m->m_len);
 		bus_dmamap_sync(sc->sc_dmat, data->map, 0,
 		    data->map->dm_mapsize, BUS_DMASYNC_POSTWRITE);
 		bus_dmamap_unload(sc->sc_dmat, data->map);