Replaced before script with addons.
diff --git a/.travis.yml b/.travis.yml
index 8ec4fe6..1df1917 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,15 +2,15 @@
 
 sudo: false
 
+addons:
+  apt:
+    packages:
+    - autoconf
+
 compiler:
   - clang
   - gcc
 
-before_script:
-  - sudo add-apt-repository ppa:dns/gnu -y
-  - sudo apt-get update -q
-  - sudo apt-get install --only-upgrade autoconf
-
 script:
     - export OMP_NUM_THREADS=1
     - export CFLAGS="-Wno-deprecated-declarations -Wdeclaration-after-statement -Wno-error=unused-variable"