diff --git a/hgext/largefiles/lfutil.py b/hgext/largefiles/lfutil.py
--- a/hgext/largefiles/lfutil.py
+++ b/hgext/largefiles/lfutil.py
@@ -342,8 +342,11 @@ def splitstandin(filename):
     else:
         return None
 
-def updatestandin(repo, standin):
-    lfile = splitstandin(standin)
+def updatestandin(repo, lfile, standin):
+    """Re-calculate hash value of lfile and write it into standin
+
+    This assumes that "lfutil.standin(lfile) == standin", for efficiency.
+    """
     file = repo.wjoin(lfile)
     if repo.wvfs.exists(lfile):
         hash = hashfile(file)
@@ -560,7 +563,7 @@ def updatestandinsbymatch(repo, match):
                     # performed and the working copy is not updated
                     # yet.
                     if repo.wvfs.exists(lfile):
-                        updatestandin(repo, fstandin)
+                        updatestandin(repo, lfile, fstandin)
 
         return match
 
@@ -586,7 +589,7 @@ def updatestandinsbymatch(repo, match):
     for fstandin in standins:
         lfile = splitstandin(fstandin)
         if lfdirstate[lfile] != 'r':
-            updatestandin(repo, fstandin)
+            updatestandin(repo, lfile, fstandin)
 
     # Cook up a new matcher that only matches regular files or
     # standins corresponding to the big files requested by the
diff --git a/hgext/largefiles/overrides.py b/hgext/largefiles/overrides.py
--- a/hgext/largefiles/overrides.py
+++ b/hgext/largefiles/overrides.py
@@ -736,7 +736,7 @@ def overriderevert(orig, ui, repo, ctx, 
         s = lfutil.lfdirstatestatus(lfdirstate, repo)
         lfdirstate.write()
         for lfile in s.modified:
-            lfutil.updatestandin(repo, lfutil.standin(lfile))
+            lfutil.updatestandin(repo, lfile, lfutil.standin(lfile))
         for lfile in s.deleted:
             fstandin = lfutil.standin(lfile)
             if (repo.wvfs.exists(fstandin)):
@@ -1417,7 +1417,7 @@ def mergeupdate(orig, repo, node, branch
                 # in this case, content of standin file is meaningless
                 # (in dctx, lfile is unknown, or normal file)
                 continue
-            lfutil.updatestandin(repo, fstandin)
+            lfutil.updatestandin(repo, lfile, fstandin)
         # mark all clean largefiles as dirty, just in case the update gets
         # interrupted before largefiles and lfdirstate are synchronized
         for lfile in oldclean: