diff --git a/mercurial/context.py b/mercurial/context.py
--- a/mercurial/context.py
+++ b/mercurial/context.py
@@ -352,12 +352,12 @@ class filectx(object):
     def size(self):
         return self._filelog.size(self._filerev)
 
-    def cmp(self, text):
-        """compare text with stored file revision
+    def cmp(self, fctx):
+        """compare with other file context
 
-        returns True if text is different than what is stored.
+        returns True if different than fctx.
         """
-        return self._filelog.cmp(self._filenode, text)
+        return self._filelog.cmp(self._filenode, fctx.data())
 
     def renamed(self):
         """check if file was actually renamed in this changeset revision
@@ -935,12 +935,12 @@ class workingfilectx(filectx):
                 raise
             return (t, tz)
 
-    def cmp(self, text):
-        """compare text with disk content
+    def cmp(self, fctx):
+        """compare with other file context
 
-        returns True if text is different than what is on disk.
+        returns True if different than fctx.
         """
-        return self._repo.wread(self._path) != text
+        return self._repo.wread(self._path) != fctx.data()
 
 class memctx(object):
     """Use memctx to perform in-memory commits via localrepo.commitctx().
diff --git a/mercurial/filemerge.py b/mercurial/filemerge.py
--- a/mercurial/filemerge.py
+++ b/mercurial/filemerge.py
@@ -135,7 +135,7 @@ def filemerge(repo, mynode, orig, fcd, f
         except IOError:
             return False
 
-    if not fco.cmp(fcd.data()): # files identical?
+    if not fco.cmp(fcd): # files identical?
         return None
 
     if fca == fco: # backwards, use working dir parent as ancestor
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1062,7 +1062,7 @@ class localrepository(repo.repository):
                 # do a full compare of any files that might have changed
                 for f in sorted(cmp):
                     if (f not in ctx1 or ctx2.flags(f) != ctx1.flags(f)
-                        or ctx1[f].cmp(ctx2[f].data())):
+                        or ctx1[f].cmp(ctx2[f])):
                         modified.append(f)
                     else:
                         fixup.append(f)
@@ -1106,7 +1106,7 @@ class localrepository(repo.repository):
                 if fn in mf1:
                     if (mf1.flags(fn) != mf2.flags(fn) or
                         (mf1[fn] != mf2[fn] and
-                         (mf2[fn] or ctx1[fn].cmp(ctx2[fn].data())))):
+                         (mf2[fn] or ctx1[fn].cmp(ctx2[fn])))):
                         modified.append(fn)
                     elif listclean:
                         clean.append(fn)
diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -73,7 +73,7 @@ class mergestate(object):
 def _checkunknown(wctx, mctx):
     "check for collisions between unknown files and files in mctx"
     for f in wctx.unknown():
-        if f in mctx and mctx[f].cmp(wctx[f].data()):
+        if f in mctx and mctx[f].cmp(wctx[f]):
             raise util.Abort(_("untracked file in working directory differs"
                                " from file in requested revision: '%s'") % f)