try fully qualified apt source
diff --git a/.travis.yml b/.travis.yml
index 6c58b3b..225cbf5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@
 addons:
   apt:
     sources:
-    - deadsnakes
+    - ppa:fkrull/deadsnakes
     packages:
     - python3.6