diff --git a/src/disk/zip.c b/src/disk/zip.c
index 5e0b63c77..ccc2fd1c2 100644
--- a/src/disk/zip.c
+++ b/src/disk/zip.c
@@ -859,7 +859,7 @@ zip_bus_speed(zip_t *dev)
 {
     double ret = -1.0;
 
-    if (dev && dev->drv && dev->drv->bus_type == ZIP_BUS_SCSI) {
+    if (dev && dev->drv && (dev->drv->bus_type == ZIP_BUS_SCSI)) {
 	dev->callback = -1.0;	/* Speed depends on SCSI controller */
 	return 0.0;
     } else {
diff --git a/src/scsi/scsi_cdrom.c b/src/scsi/scsi_cdrom.c
index 3ea4bd169..72d3b2e2a 100644
--- a/src/scsi/scsi_cdrom.c
+++ b/src/scsi/scsi_cdrom.c
@@ -606,7 +606,7 @@ scsi_cdrom_bus_speed(scsi_cdrom_t *dev)
 {
     double ret = -1.0;
 
-    if (dev->drv->bus_type == CDROM_BUS_SCSI) {
+    if (dev && dev->drv && (dev->drv->bus_type == CDROM_BUS_SCSI)) {
 	dev->callback = -1.0;	/* Speed depends on SCSI controller */
 	return 0.0;
     } else {