diff --git a/hgext/convert/common.py b/hgext/convert/common.py
--- a/hgext/convert/common.py
+++ b/hgext/convert/common.py
@@ -447,7 +447,7 @@
         if not self.path:
             return
         try:
-            fp = open(self.path, 'r')
+            fp = open(self.path, 'rb')
         except IOError as err:
             if err.errno != errno.ENOENT:
                 raise
@@ -471,7 +471,7 @@
     def __setitem__(self, key, value):
         if self.fp is None:
             try:
-                self.fp = open(self.path, 'a')
+                self.fp = open(self.path, 'ab')
             except IOError as err:
                 raise error.Abort(
                     _('could not open map file %r: %s') %
diff --git a/hgext/convert/convcmd.py b/hgext/convert/convcmd.py
--- a/hgext/convert/convcmd.py
+++ b/hgext/convert/convcmd.py
@@ -202,7 +202,7 @@
             return {}
         m = {}
         try:
-            fp = open(path, 'r')
+            fp = open(path, 'rb')
             for i, line in enumerate(util.iterfile(fp)):
                 line = line.splitlines()[0].rstrip()
                 if not line:
@@ -407,13 +407,13 @@
         authorfile = self.authorfile
         if authorfile:
             self.ui.status(_('writing author map file %s\n') % authorfile)
-            ofile = open(authorfile, 'w+')
+            ofile = open(authorfile, 'wb+')
             for author in self.authors:
                 ofile.write("%s=%s\n" % (author, self.authors[author]))
             ofile.close()
 
     def readauthormap(self, authorfile):
-        afile = open(authorfile, 'r')
+        afile = open(authorfile, 'rb')
         for line in afile:
 
             line = line.strip()
diff --git a/hgext/convert/cvs.py b/hgext/convert/cvs.py
--- a/hgext/convert/cvs.py
+++ b/hgext/convert/cvs.py
@@ -46,8 +46,8 @@
         self.tags = {}
         self.lastbranch = {}
         self.socket = None
-        self.cvsroot = open(os.path.join(cvs, "Root")).read()[:-1]
-        self.cvsrepo = open(os.path.join(cvs, "Repository")).read()[:-1]
+        self.cvsroot = open(os.path.join(cvs, "Root"), 'rb').read()[:-1]
+        self.cvsrepo = open(os.path.join(cvs, "Repository"), 'rb').read()[:-1]
         self.encoding = encoding.encoding
 
         self._connect()
@@ -141,7 +141,7 @@
                     passw = "A"
                     cvspass = os.path.expanduser("~/.cvspass")
                     try:
-                        pf = open(cvspass)
+                        pf = open(cvspass, 'rb')
                         for line in pf.read().splitlines():
                             part1, part2 = line.split(' ', 1)
                             # /1 :pserver:user@example.com:2401/cvsroot/foo
diff --git a/hgext/convert/cvsps.py b/hgext/convert/cvsps.py
--- a/hgext/convert/cvsps.py
+++ b/hgext/convert/cvsps.py
@@ -132,7 +132,7 @@
 
         # Get the real directory in the repository
         try:
-            prefix = open(os.path.join('CVS','Repository')).read().strip()
+            prefix = open(os.path.join('CVS','Repository'), 'rb').read().strip()
             directory = prefix
             if prefix == ".":
                 prefix = ""
@@ -144,7 +144,7 @@
 
         # Use the Root file in the sandbox, if it exists
         try:
-            root = open(os.path.join('CVS','Root')).read().strip()
+            root = open(os.path.join('CVS','Root'), 'rb').read().strip()
         except IOError:
             pass
 
@@ -177,7 +177,7 @@
     if cache == 'update':
         try:
             ui.note(_('reading cvs log cache %s\n') % cachefile)
-            oldlog = pickle.load(open(cachefile))
+            oldlog = pickle.load(open(cachefile, 'rb'))
             for e in oldlog:
                 if not (util.safehasattr(e, 'branchpoints') and
                         util.safehasattr(e, 'commitid') and
@@ -486,7 +486,7 @@
 
             # write the new cachefile
             ui.note(_('writing cvs log cache %s\n') % cachefile)
-            pickle.dump(log, open(cachefile, 'w'))
+            pickle.dump(log, open(cachefile, 'wb'))
         else:
             log = oldlog
 
diff --git a/hgext/convert/filemap.py b/hgext/convert/filemap.py
--- a/hgext/convert/filemap.py
+++ b/hgext/convert/filemap.py
@@ -71,7 +71,7 @@
                              (lex.infile, lex.lineno, listname, name))
                 return 1
             return 0
-        lex = shlex.shlex(open(path), path, True)
+        lex = shlex.shlex(open(path, 'rb'), path, True)
         lex.wordchars += '!@#$%^&*()-=+[]{}|;:,./<>?'
         cmd = lex.get_token()
         while cmd:
diff --git a/hgext/convert/hg.py b/hgext/convert/hg.py
--- a/hgext/convert/hg.py
+++ b/hgext/convert/hg.py
@@ -625,7 +625,7 @@
 
     def converted(self, rev, destrev):
         if self.convertfp is None:
-            self.convertfp = open(self.repo.vfs.join('shamap'), 'a')
+            self.convertfp = open(self.repo.vfs.join('shamap'), 'ab')
         self.convertfp.write('%s %s\n' % (destrev, rev))
         self.convertfp.flush()
 
diff --git a/hgext/convert/subversion.py b/hgext/convert/subversion.py
--- a/hgext/convert/subversion.py
+++ b/hgext/convert/subversion.py
@@ -231,7 +231,7 @@
 def httpcheck(ui, path, proto):
     try:
         opener = urlreq.buildopener()
-        rsp = opener.open('%s://%s/!svn/ver/0/.svn' % (proto, path))
+        rsp = opener.open('%s://%s/!svn/ver/0/.svn' % (proto, path), 'rb')
         data = rsp.read()
     except urlerr.httperror as inst:
         if inst.code != 404:
@@ -639,7 +639,7 @@
             return
         if self.convertfp is None:
             self.convertfp = open(os.path.join(self.wc, '.svn', 'hg-shamap'),
-                                  'a')
+                                  'ab')
         self.convertfp.write('%s %d\n' % (destrev, self.revnum(rev)))
         self.convertfp.flush()
 
@@ -1158,7 +1158,7 @@
 
         if created:
             hook = os.path.join(created, 'hooks', 'pre-revprop-change')
-            fp = open(hook, 'w')
+            fp = open(hook, 'wb')
             fp.write(pre_revprop_change)
             fp.close()
             util.setflags(hook, False, True)
@@ -1308,7 +1308,7 @@
             self.setexec = []
 
         fd, messagefile = tempfile.mkstemp(prefix='hg-convert-')
-        fp = os.fdopen(fd, pycompat.sysstr('w'))
+        fp = os.fdopen(fd, pycompat.sysstr('wb'))
         fp.write(commit.desc)
         fp.close()
         try: