update travis.yml
diff --git a/.travis.yml b/.travis.yml
index f90b4a9..8dd99d5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,9 @@
 language: go
 go_import_path: github.com/pkg/errors
 go:
-  - 1.5.2
+  - 1.5.4
   - 1.4.3
+  - 1.6.1
   - tip
 
 script: