diff --git a/.travis.yml b/.travis.yml
index 5b1127ed..6b15a935 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -26,7 +26,7 @@ matrix:
         apt:
           sources:
             - ubuntu-toolchain-r-test
-            - george-edison55/cmake-3.x
+            - sourceline: 'ppa:george-edison55/cmake-3.x'
           packages:
             - g++-8
             - cmake