diff --git a/VirtualBox/scripts/INSTALL_CMake.sh b/VirtualBox/scripts/INSTALL_CMake.sh
index 8e821a21..9276454f 100755
--- a/VirtualBox/scripts/INSTALL_CMake.sh
+++ b/VirtualBox/scripts/INSTALL_CMake.sh
@@ -3,9 +3,10 @@
 # optional first argument is location (e.g. /usr/local (default), $HOME)
 # If using a system location, execute with sudo
 # You need to make sure the resulting location will be in your path
+# If you want to select the CMake version, set the "ver" environment variable
 
 # Authors: Ben Thomas, Kris Thielemans
-# Copyright 2017-2018 University College London
+# Copyright 2017-2018, 2024 University College London
 
 set -e
 if [ $# -eq 0 ]
@@ -14,15 +15,17 @@ then
 else
     INSTALL_LOC=$1
 fi
-ver=3.21.3
+# default version, but can be set externally
+: ${ver=3.21.3}
 
 echo "Downloading CMake $ver in /tmp"
 cd /tmp
 # next location could be for older releases (although 3.7.2 was in a 3.7 dir, not 3.7.2)
 # wget -c https://cmake.org/files/${ver}/cmake-${ver}-Linux-x86_64.tar.gz
-wget -c https://github.com/Kitware/CMake/releases/download/v${ver}/cmake-${ver}-Linux-x86_64.tar.gz
+wget -c "https://github.com/Kitware/CMake/releases/download/v${ver}/cmake-${ver}-Linux-x86_64.tar.gz"
 
 echo "Installing CMake $ver in ${INSTALL_LOC}"
-cd ${INSTALL_LOC}
-tar xzf /tmp/cmake-${ver}-Linux-x86_64.tar.gz --strip 1
-rm /tmp/cmake-${ver}-Linux-x86_64.tar.gz
+mkdir -p "$INSTALL_LOC"
+cd "$INSTALL_LOC"
+tar xzf "/tmp/cmake-${ver}-Linux-x86_64.tar.gz" --strip 1
+rm "/tmp/cmake-${ver}-Linux-x86_64.tar.gz"