diff --git a/sys/arch/macppc/dev/wdc_obio.c b/sys/arch/macppc/dev/wdc_obio.c
index 4b6cafba254b..b64adde7d83c 100644
--- a/sys/arch/macppc/dev/wdc_obio.c
+++ b/sys/arch/macppc/dev/wdc_obio.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: wdc_obio.c,v 1.44 2006/03/29 04:16:45 thorpej Exp $	*/
+/*	$NetBSD: wdc_obio.c,v 1.45 2006/09/04 03:44:10 macallan Exp $	*/
 
 /*-
  * Copyright (c) 1998, 2003 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: wdc_obio.c,v 1.44 2006/03/29 04:16:45 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: wdc_obio.c,v 1.45 2006/09/04 03:44:10 macallan Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -130,7 +130,9 @@ wdc_obio_attach(parent, self, aux)
 	struct ata_channel *chp = &sc->sc_channel;
 	int intr, i;
 	int use_dma = 0;
-	char path[80];
+	char path[80], compat[32];
+
+	OF_getprop(ca->ca_node, "compatible", compat, sizeof(compat));
 
 	if (device_cfdata(&sc->sc_wdcdev.sc_atac.atac_dev)->cf_flags &
 	    WDC_OPTIONS_DMA) {
@@ -149,6 +151,12 @@ wdc_obio_attach(parent, self, aux)
 		return;
 	}
 
+	/* disable DMA on Heathrow */
+	if (strcmp(compat, "heathrow-ata") == 0) {
+		use_dma = 0;
+		printf(": DMA disabled");
+	}
+	
 	if (use_dma)
 		printf(": DMA transfer");
 
@@ -193,7 +201,8 @@ wdc_obio_attach(parent, self, aux)
 		if (strcmp(ca->ca_name, "ata-4") == 0) {
 			sc->sc_wdcdev.sc_atac.atac_cap |= ATAC_CAP_UDMA;
 			sc->sc_wdcdev.sc_atac.atac_udma_cap = 4;
-			sc->sc_wdcdev.sc_atac.atac_set_modes = ata4_adjust_timing;
+			sc->sc_wdcdev.sc_atac.atac_set_modes = 
+			    ata4_adjust_timing;
 		} else {
 			sc->sc_wdcdev.sc_atac.atac_set_modes = adjust_timing;
 		}