diff --git a/libvirt/config.py b/libvirt/config.py
index 7e90d0c..4d41a7d 100755
--- a/libvirt/config.py
+++ b/libvirt/config.py
@@ -135,8 +135,8 @@ def host_key_validate(data, field, value):
                     errnum += 1
             elif key in ('cpu', 'mem'):
                 if not isinstance(item, int):
-                    print('%s is not valid for %s' %
-                          (item, field), file=sys.stderr)
+                    print('%s is not valid for %s in %s' %
+                          (item, key, field), file=sys.stderr)
                     errnum += 1
     return errnum