fix travis
diff --git a/.travis.yml b/.travis.yml
index b6dbd0a..4c52744 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,3 +17,6 @@
       cargo bench --verbose --features i128;
       cargo bench --verbose --no-default-features --features i128;
     fi
+branches:
+  only:
+    - master