diff --git a/master/buildbot/newsfragments/make-slavedirectoryuploadcommand-robust.bugfix b/master/buildbot/newsfragments/make-slavedirectoryuploadcommand-robust.bugfix
new file mode 100644
index 000000000000..541fad4bae03
--- /dev/null
+++ b/master/buildbot/newsfragments/make-slavedirectoryuploadcommand-robust.bugfix
@@ -0,0 +1 @@
+:py:class: `~buildbot_worker.commands.transfer.SlaveDirectoryUploadCommand` no longer throws exceptions because the file "is used by another process" under Windows
diff --git a/worker/buildbot_worker/commands/transfer.py b/worker/buildbot_worker/commands/transfer.py
index 49773eefba76..81e17d6e8b85 100644
--- a/worker/buildbot_worker/commands/transfer.py
+++ b/worker/buildbot_worker/commands/transfer.py
@@ -214,20 +214,22 @@ def start(self):
 
         # Create temporary archive
         fd, self.tarname = tempfile.mkstemp()
-        fileobj = os.fdopen(fd, 'wb')
+        self.fp = os.fdopen(fd, "rb+")
+
         if self.compress == 'bz2':
             mode = 'w|bz2'
         elif self.compress == 'gz':
             mode = 'w|gz'
         else:
             mode = 'w'
-        archive = tarfile.open(name=self.tarname, mode=mode, fileobj=fileobj)
+        # TODO: Use 'with' when depending on Python 2.7
+        # Not possible with older versions: exceptions.AttributeError: 'TarFile' object has no attribute '__exit__'
+        archive = tarfile.open(mode=mode, fileobj=self.fp)
         archive.add(self.path, '')
         archive.close()
-        fileobj.close()
 
         # Transfer it
-        self.fp = open(self.tarname, 'rb')
+        self.fp.seek(0)
 
         self.sendStatus({'header': "sending %s" % self.path})