diff -r 9554952d36d7 -r 6923074540dd svgui/pyjs/build.py
--- a/svgui/pyjs/build.py	Wed Oct 03 15:47:59 2018 +0300
+++ b/svgui/pyjs/build.py	Thu Oct 04 11:25:42 2018 +0300
@@ -10,7 +10,7 @@
 from os.path import join, basename, abspath, split, isfile, isdir
 from hashlib import md5
 from optparse import OptionParser
-from cStringIO import StringIO
+from six.moves import cStringIO
 
 from svgui.pyjs import pyjs
 
@@ -254,7 +254,7 @@
 
     # the selector templ is added to the selectScript function
     select_tmpl = """O(["true","%s"],"%s");"""
-    script_selectors = StringIO()
+    script_selectors = cStringIO()
 
     for platform, file_prefix in app_files:
         print(select_tmpl % (platform, file_prefix), file=script_selectors)
@@ -453,7 +453,7 @@
             if dynamic:
                 mod_cache_html_output = open(join(output, mod_cache_name), "w")
             else:
-                mod_cache_html_output = StringIO()
+                mod_cache_html_output = cStringIO()
 
             print(mod_cache_html_template % dict(
                 mod_name=mod_name,