Use PyPy 2.5.1 on Travis OS X
diff --git a/.travis/install.sh b/.travis/install.sh
index f82cc4a..d42944d 100755
--- a/.travis/install.sh
+++ b/.travis/install.sh
@@ -41,8 +41,8 @@
             ;;
         pypy)
             brew upgrade pyenv
-            pyenv install pypy-2.5.0
-            pyenv global pypy-2.5.0
+            pyenv install pypy-2.5.1
+            pyenv global pypy-2.5.1
             ;;
         pypy3)
             brew upgrade pyenv