diff --git a/.travis.yml b/.travis.yml
index 7f28cb9d6d247..ba88b3ef51f0d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,7 @@
 language: python
 python:
   - "2.7"
-  - "3.5"
+  - "3.4"
 cache:
   directories:
     - $HOME/.wheelhouse/
diff --git a/panoramix/utils.py b/panoramix/utils.py
index 0d3dcef3c8ceb..c1e930cfe7ab8 100644
--- a/panoramix/utils.py
+++ b/panoramix/utils.py
@@ -113,6 +113,7 @@ def color(s):
         "#A14D83", "#4FA3AB", "#4EDED2", "#4EDED2", "#FFCA4F", "#FFC4B3",
         "#C9BF97", "#C9BF97", "#898C8C",
     ]
+    s = s.encode('utf-8')
     h = hashlib.md5(s)
     i = int(h.hexdigest(), 16)
     return colors[i % len(colors)]