diff --git a/Lib/distutils/command/upload.py b/Lib/distutils/command/upload.py
index 4926aa3e154..8b36851d256 100644
--- a/Lib/distutils/command/upload.py
+++ b/Lib/distutils/command/upload.py
@@ -125,7 +125,7 @@ def upload_file(self, command, pyversion, filename):
 
         if self.sign:
             data['gpg_signature'] = (os.path.basename(filename) + ".asc",
-                                     open(filename+".asc").read())
+                                     open(filename+".asc", "rb").read())
 
         # set up the authentication
         user_pass = (self.username + ":" + self.password).encode('ascii')
diff --git a/Misc/ACKS b/Misc/ACKS
index 514e95dbec9..efa7339e2b3 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1009,6 +1009,7 @@ Felix Wiemann
 Gerry Wiener
 Frank Wierzbicki
 Bryce "Zooko" Wilcox-O'Hearn
+Jakub Wilk
 Jason Williams
 John Williams
 Sue Williams
diff --git a/Misc/NEWS b/Misc/NEWS
index a8c274965d9..242b8f76d1a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -81,6 +81,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #10571: Fix the "--sign" option of distutils' upload command.
+  Patch by Jakub Wilk.
+
 - Issue #9559: If messages were only added, a new file is no longer
   created and renamed over the old file when flush() is called on an
   mbox, MMDF or Babyl mailbox.