diff --git a/hgext/convert/gnuarch.py b/hgext/convert/gnuarch.py
--- a/hgext/convert/gnuarch.py
+++ b/hgext/convert/gnuarch.py
@@ -284,7 +284,7 @@ class gnuarch_source(converter_source, c
             self.changes[rev].summary = self.recode(self.changes[rev].summary)
 
             # Commit revision origin when dealing with a branch or tag
-            if catlog.has_key('Continuation-of'):
+            if 'Continuation-of' in catlog:
                 self.changes[rev].continuationof = self.recode(catlog['Continuation-of'])
         except Exception:
             raise util.Abort(_('could not parse cat-log of %s') % rev)
diff --git a/hgext/win32mbcs.py b/hgext/win32mbcs.py
--- a/hgext/win32mbcs.py
+++ b/hgext/win32mbcs.py
@@ -101,7 +101,7 @@ def wrapperforlistdir(func, args, kwds):
     if args:
         args = list(args)
         args[0] = appendsep(args[0])
-    if kwds.has_key('path'):
+    if 'path' in kwds:
         kwds['path'] = appendsep(kwds['path'])
     return func(*args, **kwds)
 
diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1323,11 +1323,11 @@ def grep(ui, repo, pattern, *pats, **opt
                     continue
                 files.append(fn)
 
-                if not matches[rev].has_key(fn):
+                if fn not in matches[rev]:
                     grepbody(fn, rev, flog.read(fnode))
 
                 pfn = copy or fn
-                if not matches[parent].has_key(pfn):
+                if pfn not in matches[parent]:
                     try:
                         fnode = pctx.filenode(pfn)
                         grepbody(pfn, parent, flog.read(fnode))