Don't use shell redirection
diff --git a/.travis/install.sh b/.travis/install.sh
index 3ff723d..8e791b3 100755
--- a/.travis/install.sh
+++ b/.travis/install.sh
@@ -10,7 +10,7 @@
         brew outdated openssl || brew upgrade openssl
     fi
 
-    if which pyenv > /dev/null; then
+    if which -s pyenv; then
         eval "$(pyenv init -)"
     fi