diff --git a/mozdevice/mozdevice/devicemanager.py b/mozdevice/mozdevice/devicemanager.py
index b6be647..32434d2 100644
--- a/mozdevice/mozdevice/devicemanager.py
+++ b/mozdevice/mozdevice/devicemanager.py
@@ -6,6 +6,7 @@
 import mozlog
 import socket
 import os
+import posixpath
 import re
 import struct
 import StringIO
@@ -238,15 +239,14 @@ def mkDirs(self, filename):
         WARNING: does not create last part of the path. For example, if asked to
         create `/mnt/sdcard/foo/bar/baz`, it will only create `/mnt/sdcard/foo/bar`
         """
-        dirParts = filename.rsplit('/', 1)
-        if not self.dirExists(dirParts[0]):
+        filename = posixpath.normpath(filename)
+        containing = posixpath.dirname(filename)
+        if not self.dirExists(containing):
             parts = filename.split('/')
-            name = ""
-            for part in parts:
-                if part is parts[-1]:
-                    break
+            name = "/"
+            for part in parts[:-1]:
                 if part != "":
-                    name += '/' + part
+                    name = posixpath.join(name, part)
                     self.mkDir(name) # mkDir will check previous existence
 
     @abstractmethod
diff --git a/mozdevice/mozdevice/devicemanagerSUT.py b/mozdevice/mozdevice/devicemanagerSUT.py
index acf4c82..aadf890 100644
--- a/mozdevice/mozdevice/devicemanagerSUT.py
+++ b/mozdevice/mozdevice/devicemanagerSUT.py
@@ -368,15 +368,13 @@ def pushDir(self, localDir, remoteDir, retryLimit = None):
 
         existentDirectories = []
         for root, dirs, files in os.walk(localDir, followlinks=True):
-            parts = root.split(localDir)
+            _, subpath = root.split(localDir)
+            subpath = subpath.lstrip('/')
+            remoteRoot = posixpath.join(remoteDir, subpath)
             for f in files:
-                remoteRoot = remoteDir + '/' + parts[1]
-                if (remoteRoot.endswith('/')):
-                    remoteName = remoteRoot + f
-                else:
-                    remoteName = remoteRoot + '/' + f
+                remoteName = posixpath.join(remoteRoot, f)
 
-                if (parts[1] == ""):
+                if subpath == "":
                     remoteRoot = remoteDir
 
                 parent = os.path.dirname(remoteName)
diff --git a/mozdevice/tests/sut_mkdir.py b/mozdevice/tests/sut_mkdir.py
index 14cc658..43ab0d2 100644
--- a/mozdevice/tests/sut_mkdir.py
+++ b/mozdevice/tests/sut_mkdir.py
@@ -59,6 +59,15 @@ def test_repeated_path_part(self):
         d.mkDirs('/mnt/sdcard/foo/foo')
         a.wait()
 
+    def test_mkdirs_on_root(self):
+        cmds = [('isdir /', 'TRUE')]
+        a = MockAgent(self, commands=cmds)
+        d = mozdevice.DroidSUT('127.0.0.1', port=a.port,
+                               logLevel=mozlog.DEBUG)
+        d.mkDirs('/foo')
+
+        a.wait()
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/mozdevice/tests/sut_push.py b/mozdevice/tests/sut_push.py
index 8f2e7b7..8abd5a7 100644
--- a/mozdevice/tests/sut_push.py
+++ b/mozdevice/tests/sut_push.py
@@ -44,21 +44,21 @@ def test_push_dir(self):
         f.write(pushfile)
         f.flush()
 
-        subTests = [ { 'cmds': [ ("isdir /mnt/sdcard//baz", "TRUE"),
-                                 ("isdir /mnt/sdcard//baz", "TRUE"),
-                                 ("push /mnt/sdcard//baz/%s %s\r\n%s" %
+        subTests = [ { 'cmds': [ ("isdir /mnt/sdcard/baz", "TRUE"),
+                                 ("isdir /mnt/sdcard/baz", "TRUE"),
+                                 ("push /mnt/sdcard/baz/%s %s\r\n%s" %
                                   (os.path.basename(f.name), len(pushfile),
                                    pushfile),
                                   expectedFileResponse) ],
                        'expectException': False },
-                     { 'cmds': [ ("isdir /mnt/sdcard//baz", "TRUE"),
-                                 ("isdir /mnt/sdcard//baz", "TRUE"),
-                                 ("push /mnt/sdcard//baz/%s %s\r\n%s" %
+                     { 'cmds': [ ("isdir /mnt/sdcard/baz", "TRUE"),
+                                 ("isdir /mnt/sdcard/baz", "TRUE"),
+                                 ("push /mnt/sdcard/baz/%s %s\r\n%s" %
                                   (os.path.basename(f.name), len(pushfile),
                                    pushfile),
                                   "BADHASH") ],
                        'expectException': True },
-                     { 'cmds': [ ("isdir /mnt/sdcard//baz", "FALSE"),
+                     { 'cmds': [ ("isdir /mnt/sdcard/baz", "FALSE"),
                                  ("isdir /mnt", "FALSE"),
                                  ("mkdr /mnt",
                                   "##AGENT-WARNING## Could not create the directory /mnt") ],