diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1180,7 +1180,7 @@
     def _partialmatch(self, id):
         maybewdir = wdirhex.startswith(id)
         try:
-            partial = self.index.partialmatch(id)
+            partial = self.nodemap.partialmatch(id)
             if partial and self.hasnode(partial):
                 if maybewdir:
                     # single 'ff...' match in radix tree, ambiguous with wdir