diff --git a/.travis.yml b/.travis.yml
index 3b8f049d4..5252939de 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,6 +10,6 @@ branches:
     - master
     - stable
 before_script:
-    - sudo add-apt-repository ppa:boost-latest/ppa
+    - sudo add-apt-repository -y ppa:boost-latest/ppa
     - sudo apt-get update -qq
     - sudo apt-get install libboost-thread1.55-dev libboost-system1.55-dev