diff --git a/mercurial/crecord.py b/mercurial/crecord.py
--- a/mercurial/crecord.py
+++ b/mercurial/crecord.py
@@ -64,7 +64,7 @@
 
     curses.error
 except (ImportError, AttributeError):
-    curses = False
+    curses = None
 
 
 class fallbackerror(error.Abort):