diff --git a/hgext/convert/__init__.py b/hgext/convert/__init__.py
--- a/hgext/convert/__init__.py
+++ b/hgext/convert/__init__.py
@@ -37,6 +37,9 @@ configitem('convert', 'cvsps.cache',
 configitem('convert', 'cvsps.fuzz',
     default=60,
 )
+configitem('convert', 'cvsps.mergefrom',
+    default=None,
+)
 
 # Commands definition was moved elsewhere to ease demandload job.
 
diff --git a/hgext/convert/cvs.py b/hgext/convert/cvs.py
--- a/hgext/convert/cvs.py
+++ b/hgext/convert/cvs.py
@@ -82,7 +82,7 @@ class convert_cvs(converter_source):
             db = cvsps.createchangeset(self.ui, db,
                 fuzz=int(self.ui.config('convert', 'cvsps.fuzz')),
                 mergeto=self.ui.config('convert', 'cvsps.mergeto', None),
-                mergefrom=self.ui.config('convert', 'cvsps.mergefrom', None))
+                mergefrom=self.ui.config('convert', 'cvsps.mergefrom'))
 
             for cs in db:
                 if maxrev and cs.id > maxrev: