diff --git a/zsh/functions.zsh b/zsh/functions.zsh
index 4a14e3e..58ca7cb 100644
--- a/zsh/functions.zsh
+++ b/zsh/functions.zsh
@@ -91,13 +91,13 @@ function docker_rm_all() {
   docker rm -f `docker ps --no-trunc -aq`
 }
 function Replace () {
-	if [ "$(uname)" == "Darwin" ]; then
+	if [[ "$(uname)" == "Darwin" ]]; then
 		if [ "$#" -eq 3 ]; then
 			ag $2 -l -G $1 | xargs sed -i '' s/$2/$3/g
 		elif [ "$#" -eq 2 ]; then
 			ag $1 -l | xargs sed -i '' s/$1/$2/g
 		fi
-	elif [ "$(expr substr $(uname -s) 1 5)" == "Linux" ]; then
+	elif [[ "$(expr substr $(uname -s) 1 5)" == "Linux" ]]; then
 		if [ "$#" -eq 3 ]; then
 			ag $2 -l -G $1 | xargs sed -i s/$2/$3/g
 		elif [ "$#" -eq 2 ]; then