diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 56c5239dcf..79c7ea3c66 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -1233,10 +1233,12 @@ cleanup:
 }
 
 
-void
+int
 virDomainDiskDefAssignAddress(virDomainDiskDefPtr def)
 {
     int idx = virDiskNameToIndex(def->dst);
+    if (idx < 0)
+        return -1;
 
     switch (def->bus) {
     case VIR_DOMAIN_DISK_BUS_SCSI:
@@ -1270,6 +1272,8 @@ virDomainDiskDefAssignAddress(virDomainDiskDefPtr def)
         /* Other disk bus's aren't controller based */
         break;
     }
+
+    return 0;
 }
 
 /* Parse the XML definition for a disk
@@ -1498,8 +1502,9 @@ virDomainDiskDefParseXML(xmlNodePtr node,
     def->serial = serial;
     serial = NULL;
 
-    if (def->info.type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE)
-        virDomainDiskDefAssignAddress(def);
+    if (def->info.type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_NONE
+        && virDomainDiskDefAssignAddress(def) < 0)
+        goto error;
 
 cleanup:
     VIR_FREE(bus);
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 0540a775b5..44fff0cccd 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -1,7 +1,7 @@
 /*
  * domain_conf.h: domain XML processing
  *
- * Copyright (C) 2006-2008 Red Hat, Inc.
+ * Copyright (C) 2006-2008, 2010 Red Hat, Inc.
  * Copyright (C) 2006-2008 Daniel P. Berrange
  *
  * This library is free software; you can redistribute it and/or
@@ -855,7 +855,7 @@ int virDomainDiskInsert(virDomainDefPtr def,
                         virDomainDiskDefPtr disk);
 void virDomainDiskInsertPreAlloced(virDomainDefPtr def,
                                    virDomainDiskDefPtr disk);
-void virDomainDiskDefAssignAddress(virDomainDiskDefPtr def);
+int virDomainDiskDefAssignAddress(virDomainDiskDefPtr def);
 
 int virDomainControllerInsert(virDomainDefPtr def,
                               virDomainControllerDefPtr controller);
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index f2d36f71c0..902eecb0d5 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -4815,7 +4815,13 @@ qemuParseCommandLineDisk(const char *val,
     else
         def->dst[2] = 'a' + idx;
 
-    virDomainDiskDefAssignAddress(def);
+    if (virDomainDiskDefAssignAddress(def) < 0) {
+        qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                        _("invalid device name '%s'"), def->dst);
+        virDomainDiskDefFree(def);
+        def = NULL;
+        /* fall through to "cleanup" */
+    }
 
 cleanup:
     for (i = 0 ; i < nkeywords ; i++) {
@@ -5623,7 +5629,8 @@ virDomainDefPtr qemuParseCommandLine(virCapsPtr caps,
                 goto no_memory;
             }
 
-            virDomainDiskDefAssignAddress(disk);
+            if (virDomainDiskDefAssignAddress(disk) < 0)
+                goto error;
 
             if (VIR_REALLOC_N(def->disks, def->ndisks+1) < 0) {
                 virDomainDiskDefFree(disk);