diff --git a/arch/install-config.sh b/arch/install-config.sh
index f0a0398..95fb2b3 100755
--- a/arch/install-config.sh
+++ b/arch/install-config.sh
@@ -6,7 +6,7 @@
 # The configuration is adapted from the Ubuntu 16.04 script.
 #
 
-if [ $(id -u) -ne 0 ]; then
+if [ "$(id -u)" -ne 0 ]; then
     echo 'This script must be run with root privileges' >&2
     exit 1
 fi
diff --git a/arch/makepkg.sh b/arch/makepkg.sh
index c2d8eed..d1fe6ca 100755
--- a/arch/makepkg.sh
+++ b/arch/makepkg.sh
@@ -4,7 +4,7 @@
 # This script is for Arch Linux to download and install XRDP+XORGXRDP
 #
 
-if [ $(id -u) -eq 0 ]; then
+if [ "$(id -u)" -eq 0 ]; then
     echo 'This script must be run as a non-root user, as building packages as root is unsupported.' >&2
     exit 1
 fi
@@ -17,14 +17,14 @@ sudo pacman -Syu --needed --noconfirm base base-devel git
 
 # Create a build directory in tmpfs
 TMPDIR=$(mktemp -d)
-pushd $TMPDIR
+pushd "$TMPDIR" || exit
 
 ###############################################################################
 # XRDP
 #
 (
 	git clone https://aur.archlinux.org/xrdp.git
-	cd xrdp
+	cd xrdp || exit
 	makepkg -sri --noconfirm
 )
 ###############################################################################
@@ -32,7 +32,7 @@ pushd $TMPDIR
 # Devel version, because release version includes a bug crashing gnome-settings-daemon
 (
 	git clone https://aur.archlinux.org/xorgxrdp-devel-git.git
-	cd xorgxrdp-devel-git
+	cd xorgxrdp-devel-git || exit
 	makepkg -sri --noconfirm
 )
 ###############################################################################
diff --git a/ubuntu/16.04/config-user.sh b/ubuntu/16.04/config-user.sh
index b061f68..3e4d1ea 100644
--- a/ubuntu/16.04/config-user.sh
+++ b/ubuntu/16.04/config-user.sh
@@ -7,7 +7,7 @@
 # Major thanks to: http://c-nergy.be/blog/?p=10752 for the tips.
 #
 
-if [ ! $(id -u) ]; then
+if [ ! "$(id -u)" ]; then
     echo 'This script must be run with root privileges' >&2
     exit 1
 fi
diff --git a/ubuntu/16.04/install.sh b/ubuntu/16.04/install.sh
index 72c399e..a306456 100644
--- a/ubuntu/16.04/install.sh
+++ b/ubuntu/16.04/install.sh
@@ -11,7 +11,7 @@
 # Update our machine to the latest code if we need to.
 #
 
-if [ $(id -u) -ne 0 ]; then
+if [ "$(id -u)" -ne 0 ]; then
     echo 'This script must be run with root privileges' >&2
     exit 1
 fi
@@ -48,7 +48,7 @@ if [ ! -d $XRDP_PATH ]; then
 fi
 
 # Configure XRDP
-cd $XRDP_PATH
+cd $XRDP_PATH || exit
 ./bootstrap
 ./configure --enable-ipv6 --enable-jpeg --enable-fuse --enable-rfxcodec --enable-opus --enable-painter --enable-vsock
 
@@ -121,7 +121,7 @@ if [ ! -d $XORGXRDP_PATH ]; then
 fi
 
 # Configure XORGXRDP
-cd $XORGXRDP_PATH
+cd $XORGXRDP_PATH || exit
 ./bootstrap
 ./configure
 
diff --git a/ubuntu/18.04/install.sh b/ubuntu/18.04/install.sh
index 92b352c..8ebf7b6 100644
--- a/ubuntu/18.04/install.sh
+++ b/ubuntu/18.04/install.sh
@@ -11,7 +11,7 @@
 # Update our machine to the latest code if we need to.
 #
 
-if [ $(id -u) -ne 0 ]; then
+if [ "$(id -u)" -ne 0 ]; then
     echo 'This script must be run with root privileges' >&2
     exit 1
 fi