diff --git a/nova/virt/disk/nbd.py b/nova/virt/disk/nbd.py
index 029fecaf2e0..1839b2d9031 100644
--- a/nova/virt/disk/nbd.py
+++ b/nova/virt/disk/nbd.py
@@ -54,6 +54,9 @@ class Mount(mount.Mount):
     _DEVICES = ['/dev/nbd%s' % i for i in range(FLAGS.max_nbd_devices)]
 
     def _allocate_nbd(self):
+        if not os.path.exists("/sys/block/nbd0"):
+            self.error = _('nbd unavailable: module not loaded')
+            return None
         while True:
             if not self._DEVICES:
                 # really want to log this info, not raise