diff --git a/install-dev-dependencies.sh b/install-dev-dependencies.sh
index db3a50063790..767dbae82d75 100755
--- a/install-dev-dependencies.sh
+++ b/install-dev-dependencies.sh
@@ -11,27 +11,27 @@ if [ "$1" != "--no-prompt" ]; then
   echo
   echo -n "Are you sure you want to continue? [y/N]: "
   read CONTINUE
-  CONTINUE=`echo $CONTINUE | xargs | head -c 1 | awk '{print tolower($0)}'`
+  CONTINUE=$(echo "$CONTINUE" | xargs | head -c 1 | awk '{print tolower($0)}')
   if [ "$CONTINUE" != "y" ]; then
     exit
   fi
   echo
 fi
 
-if [ $UID != 0 ]; then
+if [ "$UID" != 0 ]; then
   SUDO_SHIM=sudo
 fi
 
-if [ "`uname -m`" == "x86_64" ]; then
+if [ "$(uname -m)" == "x86_64" ]; then
   ARCH=64
 else
   ARCH=32
 fi
 
 # debian based installation
-if type apt-get>/dev/null 2>&1;  then
-  $SUDO_SHIM apt-get update
-  $SUDO_SHIM apt-get install -y lsb-release
+if type apt-get >/dev/null 2>&1; then
+  "$SUDO_SHIM" apt-get update
+  "$SUDO_SHIM" apt-get install -y lsb-release
   BROWSERS="firefox chromium-browser"
   CHROMEDRIVER="chromium-chromedriver"
   if [[ "$(lsb_release -is)" == "Debian" ]]; then
@@ -41,19 +41,19 @@ if type apt-get>/dev/null 2>&1;  then
     BROWSERS="iceweasel chromium"
     CHROMEDRIVER="chromedriver"
   fi
-  $SUDO_SHIM apt-get install -y libxml2-dev libxml2-utils libxslt1-dev \
-    python3.6-dev $BROWSERS zip sqlite3 python3-pip libcurl4-openssl-dev xvfb \
-    libssl-dev git curl $CHROMEDRIVER
-  if ! type geckodriver >/dev/null 2>&1;  then
+  "$SUDO_SHIM" apt-get install -y libxml2-dev libxml2-utils libxslt1-dev \
+    python3.6-dev "$BROWSERS" zip sqlite3 python3-pip libcurl4-openssl-dev xvfb \
+    libssl-dev git curl "$CHROMEDRIVER"
+  if ! type geckodriver >/dev/null 2>&1; then
     curl -LO "https://github.com/mozilla/geckodriver/releases/download/v0.24.0/geckodriver-v0.24.0-linux$ARCH.tar.gz"
     tar -zxvf "geckodriver-v0.24.0-linux$ARCH.tar.gz"
     rm -f "geckodriver-v0.24.0-linux$ARCH.tar.gz"
-    $SUDO_SHIM mv geckodriver /usr/bin/geckodriver
-    $SUDO_SHIM chown root /usr/bin/geckodriver
-    $SUDO_SHIM chmod 755 /usr/bin/geckodriver
+    "$SUDO_SHIM" mv geckodriver /usr/bin/geckodriver
+    "$SUDO_SHIM" chown root /usr/bin/geckodriver
+    "$SUDO_SHIM" chmod 755 /usr/bin/geckodriver
   fi
-  if [ ! -f /usr/lib/chromium-browser/chromedriver ] && [ -f `which chromedriver` ]; then
-    $SUDO_SHIM ln -s `which chromedriver` /usr/lib/chromium-browser/chromedriver
+  if [ ! -f /usr/lib/chromium-browser/chromedriver ] && [ -f "$(which chromedriver)" ]; then
+    "$SUDO_SHIM" ln -s "$(which chromedriver)" /usr/lib/chromium-browser/chromedriver
   fi
 
 # macOS installation
@@ -61,42 +61,42 @@ elif type brew >/dev/null 2>&1; then
   brew list python &>/dev/null || brew install python
   brew cask install chromedriver
   brew install libxml2 gnu-sed
-  if ! echo $PATH | grep -ql /usr/local/bin ; then
+  if ! echo "$PATH" | grep -ql /usr/local/bin; then
     echo '/usr/local/bin not found in $PATH, please add it.'
   fi
 
 # distros that use rpm (Fedora, Suse, CentOS) installation
 elif type dnf >/dev/null 2>&1; then
-  $SUDO_SHIM dnf install -y firefox gcc git libcurl-devel libxml2-devel \
+  "$SUDO_SHIM" dnf install -y firefox gcc git libcurl-devel libxml2-devel \
     libxslt-devel python3-devel redhat-rpm-config xorg-x11-server-Xvfb which \
     findutils procps openssl openssl-devel chromium GConf2
   if ! type chromedriver >/dev/null; then
     curl -O "https://chromedriver.storage.googleapis.com/2.23/chromedriver_linux$ARCH.zip"
     unzip "chromedriver_linux$ARCH.zip"
     rm -f "chromedriver_linux$ARCH.zip"
-    $SUDO_SHIM mv chromedriver /usr/bin/chromedriver
-    $SUDO_SHIM chown root /usr/bin/chromedriver
-    $SUDO_SHIM chmod 755 /usr/bin/chromedriver
+    "$SUDO_SHIM" mv chromedriver /usr/bin/chromedriver
+    "$SUDO_SHIM" chown root /usr/bin/chromedriver
+    "$SUDO_SHIM" chmod 755 /usr/bin/chromedriver
   fi
-  if ! type geckodriver >/dev/null 2>&1;  then
+  if ! type geckodriver >/dev/null 2>&1; then
     curl -LO "https://github.com/mozilla/geckodriver/releases/download/v0.24.0/geckodriver-v0.24.0-macos.tar.gz"
     tar -zxvf "geckodriver-v0.24.0-macos.tar.gz"
     rm -f "geckodriver-v0.24.0-macos.tar.gz"
-    $SUDO_SHIM mv geckodriver /usr/bin/geckodriver
-    $SUDO_SHIM chown root /usr/bin/geckodriver
-    $SUDO_SHIM chmod 755 /usr/bin/geckodriver
+    "$SUDO_SHIM" mv geckodriver /usr/bin/geckodriver
+    "$SUDO_SHIM" chown root /usr/bin/geckodriver
+    "$SUDO_SHIM" chmod 755 /usr/bin/geckodriver
   fi
   # This is needed for Firefox on some systems. See here for more information:
   # https://github.com/EFForg/https-everywhere/pull/5584#issuecomment-238655443
   if [ ! -f /var/lib/dbus/machine-id ]; then
-    $SUDO_SHIM sh -c 'dbus-uuidgen > /var/lib/dbus/machine-id'
+    "$SUDO_SHIM" sh -c 'dbus-uuidgen > /var/lib/dbus/machine-id'
   fi
   export PYCURL_SSL_LIBRARY=openssl
 else
-    echo \
-    "Your distro isn't supported by this script yet!"\
+  echo \
+    "Your distro isn't supported by this script yet!" \
     "Please install dependencies manually."
-    exit
+  exit
 fi
 
 # Get the addon SDK submodule and rule checker