diff --git a/mercurial/utils/procutil.py b/mercurial/utils/procutil.py
--- a/mercurial/utils/procutil.py
+++ b/mercurial/utils/procutil.py
@@ -107,11 +107,11 @@
 
     def write(self, s):
         write1 = self.orig.write
-        m = memoryview(s)
-        total_to_write = len(s)
+        v = encoding.strfromlocal(s)
+        total_to_write = len(v)
         total_written = 0
         while total_written < total_to_write:
-            c = write1(m[total_written:])
+            c = write1(v[total_written:])
             if c:
                 total_written += c
         return total_written
@@ -147,11 +147,11 @@
 if sys.stdout is None:
     stdout = BadFile()
 else:
-    stdout = _make_write_all(sys.stdout.buffer)
+    stdout = _make_write_all(getattr(sys.stdout, 'buffer', sys.stdout))
 if sys.stderr is None:
     stderr = BadFile()
 else:
-    stderr = _make_write_all(sys.stderr.buffer)
+    stderr = _make_write_all(getattr(sys.stderr, 'buffer', sys.stderr))
 
 if pycompat.iswindows:
     # Work around Windows bugs.