diff --git a/src/disk/zip.c b/src/disk/zip.c
index 8c03f861a..85f4e677f 100644
--- a/src/disk/zip.c
+++ b/src/disk/zip.c
@@ -866,7 +866,8 @@ zip_bus_speed(zip_t *dev)
 	if (dev && dev->drv)
 		ret = ide_atapi_get_period(dev->drv->ide_channel);
 	if (ret == -1.0) {
-		dev->callback = -1.0;
+		if (dev)
+			dev->callback = -1.0;
 		return 0.0;
 	} else
 		return ret * 1000000.0;
diff --git a/src/scsi/scsi_cdrom.c b/src/scsi/scsi_cdrom.c
index 3667567fc..cb3895a4c 100644
--- a/src/scsi/scsi_cdrom.c
+++ b/src/scsi/scsi_cdrom.c
@@ -613,7 +613,8 @@ scsi_cdrom_bus_speed(scsi_cdrom_t *dev)
 	if (dev && dev->drv)
 		ret = ide_atapi_get_period(dev->drv->ide_channel);
 	if (ret == -1.0) {
-		dev->callback = -1.0;
+		if (dev)
+			dev->callback = -1.0;
 		return 0.0;
 	} else
 		return ret * 1000000.0;