diff --git a/.travis.yml b/.travis.yml
index 58bd361..5d2a0de 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,7 +13,7 @@ cache:
 
 env:
   global:
-    - BOOTSTRAP_VERSION=3
+    - BOOTSTRAP_VERSION=4
 
 jobs:
   include: