diff --git a/build.py b/build.py
index c9b132aa..d22c55e5 100755
--- a/build.py
+++ b/build.py
@@ -682,6 +682,7 @@ def uploadPackage(fileName, options, mask=defaultMask, keep=75):
     space is not overly consumed. It is assumed that if the files are in
     sorted order then the end of the list will be the newest files.
     """
+    fileName = os.path.relpath(fileName)
     fileName = fileName.replace('\\', '/')
     msg("Uploading %s..." % fileName)
 
@@ -1017,7 +1018,7 @@ def cmd_docset_py(options, args):
     # build the tarball
     msg('Archiving Phoenix docset...')
     rootname = "wxPython-docset-{}".format(cfg.VERSION)
-    tarfilename = os.path.join(phoenixDir(), 'dist', '{}.tar.gz'.format(rootname))
+    tarfilename = posixjoin(phoenixDir(), 'dist', '{}.tar.gz'.format(rootname))
     if os.path.exists(tarfilename):
         os.remove(tarfilename)
     with tarfile.open(name=tarfilename, mode="w:gz") as tarball:
@@ -1171,7 +1172,7 @@ def cmd_bdist_docs(options, args):
 
     msg("Archiving wxPython Phoenix documentation...")
     rootname = "%s-docs-%s" % (baseName, cfg.VERSION)
-    tarfilename = os.path.join(phoenixDir(), 'dist', '%s.tar.gz' % rootname)
+    tarfilename = posixjoin(phoenixDir(), 'dist', '%s.tar.gz' % rootname)
 
     if not os.path.exists('dist'):
         os.makedirs('dist')
@@ -2070,7 +2071,7 @@ def cmd_sdist(options, args):
     # build the tarball
     msg('Archiving Phoenix source...')
     rootname = "%s-%s" % (baseName, cfg.VERSION)
-    tarfilename = os.path.join(phoenixDir(), 'dist', '%s.tar.gz' % rootname)
+    tarfilename = posixjoin(phoenixDir(), 'dist', '%s.tar.gz' % rootname)
     if os.path.exists(tarfilename):
         os.remove(tarfilename)
     pwd = pushDir(PDEST)
@@ -2122,7 +2123,7 @@ def cmd_sdist_demo(options, args):
     # build the tarball
     msg('Archiving Phoenix demo and samples...')
     rootname = "%s-demo-%s" % (baseName, cfg.VERSION)
-    tarfilename = os.path.join(phoenixDir(), 'dist', '%s.tar.gz' % rootname)
+    tarfilename = posixjoin(phoenixDir(), 'dist', '%s.tar.gz' % rootname)
     if os.path.exists(tarfilename):
         os.remove(tarfilename)
     pwd = pushDir(PDEST)
@@ -2160,7 +2161,7 @@ def cmd_bdist(options, args):
     if isWindows and PYTHON_ARCH == '64bit':
         platform = 'win64'
     rootname = "%s-%s-%s-py%s" % (baseName, cfg.VERSION, platform, PYVER)
-    tarfilename = os.path.join(phoenixDir(), 'dist', '%s.tar.gz' % rootname)
+    tarfilename = posixjoin(phoenixDir(), 'dist', '%s.tar.gz' % rootname)
 
     if not os.path.exists('dist'):
         os.makedirs('dist')