diff --git a/README.md b/README.md
index c3f5f21a..c5d030ce 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,7 @@ E.g., to install `rsync`, `git` and `nginx` OS packages and `apprise` python pac
 
 ## Notes:
 - Package names entered should match the names in the relevant distro repo: https://pkgs.alpinelinux.org/packages or https://packages.ubuntu.com/
+- To install a specific version of a package include it in the name e.g. `apprise==1.10.0`. Note that `apt` requires a single `=`, while `apk` and `pip` use double `==`.
 - Setting the env var `INSTALL_PIP_PACKAGES` will result in automatic install of the `python3-dev` and `python3-pip` OS packages, updating of `pip` to the latest version and installation of the latest `setuptools` and `wheel` packages to set up the necessary environment.
 - Any other OS dependency such as `make` or `git`, which may be needed by the pip install process, should be manually added to `INSTALL_PACKAGES`.
 - The OS packages defined will be installed first, followed by the pip packages.
diff --git a/root/etc/s6-overlay/s6-rc.d/init-mod-universal-package-install-add-package/run b/root/etc/s6-overlay/s6-rc.d/init-mod-universal-package-install-add-package/run
index 0df05cf7..052edf51 100755
--- a/root/etc/s6-overlay/s6-rc.d/init-mod-universal-package-install-add-package/run
+++ b/root/etc/s6-overlay/s6-rc.d/init-mod-universal-package-install-add-package/run
@@ -1,32 +1,31 @@
 #!/usr/bin/with-contenv bash
+# shellcheck shell=bash
 
 # Exit if no installable packages are provided
-if [ -z "${INSTALL_PACKAGES+x}" ] && [ -z "${INSTALL_PIP_PACKAGES+x}" ]; then
-    echo "**** No packages to install ****"
+if [[ -z "${INSTALL_PACKAGES+x}" ]] && [[ -z "${INSTALL_PIP_PACKAGES+x}" ]]; then
+    echo "[pkg-install-init] **** No packages to install ****"
     exit 0
 fi
 
-if [ -n "${INSTALL_PIP_PACKAGES}" ] && [ -f /usr/bin/apt ]; then
+if [[ -n "${INSTALL_PIP_PACKAGES}" ]] && [[ -f /usr/bin/apt ]]; then
     echo "\
         python3-dev \
         python3-pip" >> /mod-repo-packages-to-install.list
-elif [ -n "${INSTALL_PIP_PACKAGES}" ] && [ -f /sbin/apk ]; then
+elif [[ -n "${INSTALL_PIP_PACKAGES}" ]] && [[ -f /sbin/apk ]]; then
     echo "\
         python3-dev \
         py3-pip" >> /mod-repo-packages-to-install.list
 fi
 
-
-#Split list of packages on delimiter '|'
-IFS='|'
-INSTALL_PACKAGES=(${INSTALL_PACKAGES})
-for PKG in "${INSTALL_PACKAGES[@]}"; do
-    echo "**** Adding ${PKG} to OS package install list ****"
+# Split list of packages on delimiter '|'
+IFS="|" read -r -a SPLIT_INSTALL_PACKAGES <<< "${INSTALL_PACKAGES}"
+for PKG in "${SPLIT_INSTALL_PACKAGES[@]}"; do
+    echo "[pkg-install-init] **** Adding ${PKG} to OS package install list ****"
     echo "${PKG}" >> /mod-repo-packages-to-install.list
 done
 
-INSTALL_PIP_PACKAGES=(${INSTALL_PIP_PACKAGES})
-for PKG in "${INSTALL_PIP_PACKAGES[@]}"; do
-    echo "**** Adding ${PKG} to pip install list ****"
+IFS="|" read -r -a SPLIT_INSTALL_PIP_PACKAGES <<< "${INSTALL_PIP_PACKAGES}"
+for PKG in "${SPLIT_INSTALL_PIP_PACKAGES[@]}"; do
+    echo "[pkg-install-init] **** Adding ${PKG} to pip install list ****"
     echo "${PKG}" >> /mod-pip-packages-to-install.list
 done