diff --git a/install.sh b/install.sh
index ae20b26..d053a3b 100755
--- a/install.sh
+++ b/install.sh
@@ -17,7 +17,7 @@ fi
 
 # Prevent concurrent runs
 readonly install_lock_file="$dotfiles_dir/.dotlock"
-if [ -f $install_lock_file ]; then
+if [ -f "$install_lock_file" ]; then
     printf "Failed: ${C_RED}Script already running${C_NC}\n"
     printf "Please wait for script to exit or ${C_YELLOW}make clean${C_NC}\n"
     exit 1
@@ -27,13 +27,13 @@ touch "$install_lock_file" # Requires clean
 # Run all install scripts
 readonly install_dir="$dotfiles_dir/install"
 readonly script_filter="$install_dir/*.sh"
-for script in $script_filter; do
+for script in "$script_filter"; do
 
     # Avoid pattern matching self
     [ -e "$script" ] || continue
 
     # Log execution
-    script_name=$(basename "$script" ".sh")
+    script_name="$(basename "$script" ".sh")"
     printf "Running ${C_YELLOW}$script_name${C_NC}...\n${C_DGRAY}"
 
     # Run and indent output
diff --git a/install/00-apt.sh b/install/00-apt.sh
index cd2a0ca..2c2c32e 100644
--- a/install/00-apt.sh
+++ b/install/00-apt.sh
@@ -11,5 +11,5 @@ update
 upgrade
 
 # Package installs
-readonly package_list=$(cat $install_dir/$package_list_file)
+readonly package_list="$(cat $install_dir/$package_list_file)"
 install -y "$package_list"
diff --git a/install/01-fish.sh b/install/01-fish.sh
index 5f2ce3d..1272ea2 100644
--- a/install/01-fish.sh
+++ b/install/01-fish.sh
@@ -23,7 +23,7 @@ printf "fish is installed\n"
 fish --version
 
 # 2. fish shell is default login shell
-readonly fish_path=$(which fish)
+readonly fish_path="$(which fish)"
 if [ "$SHELL" != fish_path ]; then
 
     # Update default login shell
diff --git a/install/12-docker.sh b/install/12-docker.sh
index a08f6a0..441b478 100644
--- a/install/12-docker.sh
+++ b/install/12-docker.sh
@@ -41,7 +41,8 @@ if not_installed "docker-compose"; then
     printf "Installing docker-compose...\n"
 
     # Docker-compose
-    curl -L https://github.com/docker/compose/releases/download/1.21.2/docker-compose-$(uname -s)-$(uname -m) -o /usr/local/bin/docker-compose
+    readonly docker_compose_url="https://github.com/docker/compose/releases/download/1.21.2/docker-compose-$(uname -s)-$(uname -m)"
+    curl -L docker_compose_url -o /usr/local/bin/docker-compose
     sudo chmod +x /usr/local/bin/docker-compose
 
 fi
@@ -56,7 +57,7 @@ fi
 printf "group '$docker_group' is created\n"
 
 # 4. user is in docker group
-if ! groups $USER | grep -q "\b$docker_group\b"; then
+if ! groups "$USER" | grep -q "\b$docker_group\b"; then
     sudo usermod -aG docker "$USER"
 fi
 printf "user '$USER' is in '$docker_group' group\n"
diff --git a/utils.sh b/utils.sh
index a55696e..cf0dd29 100644
--- a/utils.sh
+++ b/utils.sh
@@ -17,7 +17,7 @@ upgrade() {
 
 # @arg $1 packages to install
 install() {
-    sudo apt-get install -y $1
+    sudo apt-get install -y "$1"
 }
 
 # @arg $1 repository to add
@@ -27,13 +27,13 @@ app_ppa() {
 
 # @arg $1 url to add
 add_key() {
-    curl -fsSL $1 | sudo apt-key add -
+    curl -fsSL "$1" | sudo apt-key add -
 }
 
 # @arg $1 URL to run
 # @arg $2 binary to use
 run() {
-    curl -fsSL $1 | $2
+    curl -fsSL "$1" | "$2"
 }
 
 # Symlink contents of source folder to target
@@ -41,7 +41,7 @@ run() {
 # @arg $1 source folder
 # @arg $2 target folder
 link_folder() {
-    cp -srf $1 $2
+    cp -srf "$1" "$2"
 }
 
 indent() { sed 's/^/  /'; }