--- a/hgext/gpg.py	Mon Feb 13 20:06:38 2017 +0530
+++ b/hgext/gpg.py	Mon Feb 13 22:15:28 2017 +0530
@@ -18,6 +18,7 @@
     error,
     match,
     node as hgnode,
+    pycompat,
     util,
 )
 
@@ -44,11 +45,11 @@
         try:
             # create temporary files
             fd, sigfile = tempfile.mkstemp(prefix="hg-gpg-", suffix=".sig")
-            fp = os.fdopen(fd, 'wb')
+            fp = os.fdopen(fd, pycompat.sysstr('wb'))
             fp.write(sig)
             fp.close()
             fd, datafile = tempfile.mkstemp(prefix="hg-gpg-", suffix=".txt")
-            fp = os.fdopen(fd, 'wb')
+            fp = os.fdopen(fd, pycompat.sysstr('wb'))
             fp.write(data)
             fp.close()
             gpgcmd = ("%s --logger-fd 1 --status-fd 1 --verify "