diff --git a/roles/common/files/pip_check_requirements_upgrades.sh b/roles/common/files/pip_check_requirements_upgrades.sh
index 0ed3d5030ce8e4fb97a0e6d8d1b692c16e3f8cce..9b10d6943148db27c93fef7ef80d9338af619227 100755
--- a/roles/common/files/pip_check_requirements_upgrades.sh
+++ b/roles/common/files/pip_check_requirements_upgrades.sh
@@ -104,7 +104,7 @@ EOF
 # Set-up colours for message printing if we're not piping and terminal is
 # capable of outputting the colors.
 _color_terminal=$(tput colors 2>&1)
-if [[ -t 1 ]] && (( ${_color_terminal} > 0 )); then
+if [[ -t 1 ]] && (( _color_terminal > 0 )); then
     _text_bold=$(tput bold)
     _text_white=$(tput setaf 7)
     _text_blue=$(tput setaf 6)
@@ -179,7 +179,7 @@ while getopts "V:qdvh" opt; do
     esac
 done
 i=$OPTIND
-shift $(($i-1))
+shift $(( i-1 ))
 
 
 if [[ ${#@} == 0 ]]; then
@@ -202,6 +202,7 @@ if [[ -n $virtualenv && ! -f $virtualenv/bin/activate ]]; then
 fi
 
 # Activate the virtual environment if it was specified.
+# shellcheck disable=SC1090 # no point in validating external script
 [[ -n $virtualenv ]] && source "$virtualenv/bin/activate"
 
 # Verify pip-compile is available.
@@ -271,8 +272,8 @@ for environment in "$config_dir"/*; do
         # versioning information.
         new=$(echo "$new" | sed -e 's/[[:blank:]]*#.*//' | grep -v "^$" | sort -u)
 
-        debug "Current requirements:\n$(echo "$current")"
-        debug "New requirements:\n$(echo "$new")"
+        debug "Current requirements:\n$current\n"
+        debug "New requirements:\n$new\n"
 
         # Run diff, storing the output and result.
         # This is using Bash process substitution, which helps avoid