diff --git a/hg-fast-export.py b/hg-fast-export.py
index 3b1f267..9586b7c 100755
--- a/hg-fast-export.py
+++ b/hg-fast-export.py
@@ -334,7 +334,7 @@ def export_commit(ui,repo,revision,old_marks,max,count,authors,
   man=ctx.manifest()
   added,changed,removed,type=[],[],[],''
 
-  if len(parents) == 0:
+  if not parents:
     # first revision: feed in full manifest
     added=files
     type='full'