diff --git a/build/install_deps.sh b/build/install_deps.sh
index 0bdd6df01..c31b010f0 100755
--- a/build/install_deps.sh
+++ b/build/install_deps.sh
@@ -40,9 +40,12 @@ set -eu
 if $LINUX; then
   INSTALL="$SUDO apt-get install --no-install-recommends -y"
   $INSTALL build-essential libssl-dev libffi-dev libgmp3-dev python2.7-dev libsecret-1-dev curl
-elif $OSX && ! cmd_exists brew ; then
-  /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
-  brew update
+elif $OSX; then
+  if ! cmd_exists brew; then
+    /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
+  else
+    brew update
+  fi
 fi