diff --git a/src/esx/esx_vmx.c b/src/esx/esx_vmx.c
index 647e720bc1b78b372691b7dd8f92d60e3cba30f2..c965e0017907d9481bbe1a1bae695b76226900cc 100644
--- a/src/esx/esx_vmx.c
+++ b/src/esx/esx_vmx.c
@@ -570,11 +570,12 @@ esxVMX_GatherSCSIControllers(virDomainDefPtr def, char *virtualDev[4],
 
         if (virtualDev[controller] == NULL) {
             virtualDev[controller] = disk->driverName;
-        } else if (STRCASENEQ(virtualDev[controller], disk->driverName)) {
+        } else if (disk->driverName == NULL ||
+                   STRCASENEQ(virtualDev[controller], disk->driverName)) {
             ESX_ERROR(VIR_ERR_INTERNAL_ERROR,
                       _("Inconsistent driver usage ('%s' is not '%s') on SCSI "
                         "controller index %d"), virtualDev[controller],
-                      disk->driverName, controller);
+                      disk->driverName ? disk->driverName : "?", controller);
             return -1;
         }
     }