diff --git a/blivet/populator/populator.py b/blivet/populator/populator.py
index c237ac422..d8b2f6cf9 100644
--- a/blivet/populator/populator.py
+++ b/blivet/populator/populator.py
@@ -110,12 +110,13 @@ def _add_slave_devices(self, info):
             path = os.path.normpath("%s/%s" % (slave_dir, slave_name))
             slave_info = udev.get_device(os.path.realpath(path))
 
+            if not slave_info:
+                msg = "unable to get udev info for %s" % slave_name
+                raise DeviceTreeError(msg)
+
             # cciss in sysfs is "cciss!cXdYpZ" but we need "cciss/cXdYpZ"
             slave_name = udev.device_get_name(slave_info).replace("!", "/")
 
-            if not slave_info:
-                log.warning("unable to get udev info for %s", slave_name)
-
             slave_dev = self.get_device_by_name(slave_name)
             if not slave_dev and slave_info:
                 # we haven't scanned the slave yet, so do it now