diff --git a/blivet/devicetree.py b/blivet/devicetree.py
index 97dd6d4b0..8be855aa1 100644
--- a/blivet/devicetree.py
+++ b/blivet/devicetree.py
@@ -255,7 +255,7 @@ def _preProcessActions(self):
             else:
                 raise RuntimeError("partitions in use on disks with changes "
                                    "pending: %s" %
-                                   ",".join(p.name for p in problematic))
+                                   ",".join(problematic))
 
         log.info("resetting parted disks...")
         for device in self.devices: