diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000..0cfcba5
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,25 @@
+# Pre-commit hooks to run tests and ensure code is cleaned.
+# See https://pre-commit.com for more information
+---
+repos:
+  - repo: https://github.com/codespell-project/codespell
+    rev: v2.2.2
+    hooks:
+      - id: codespell
+        args:
+          - --ignore-words-list=exten
+          - --skip="./.*,*.csv,*.json,*.ini,*.subject,*.txt,*.html,*.log,*.conf"
+          - --quiet-level=2
+          - --ignore-regex=.*codespell-ignore$
+          #- --write-changes  # Uncomment to write changes
+        exclude_types: [csv, json]
+  - repo: https://github.com/adrienverge/yamllint
+    rev: v1.32.0
+    hooks:
+      - id: yamllint
+        ignore: .github/
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: v2.7.1
+    hooks:
+      - id: prettier
+        args: ["--print-width", "100"]
diff --git a/README.md b/README.md
index 508c11a..f670706 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@ Checks are done by running Icinga/Nagios compatible check plugins inside contain
 - `/usr/lib/nagios/plugins/check_apt`: for Debian based image, provide by the `monitoring-plugins-basic` debian package
 - `/usr/lib/nagios/plugins/check_apk`: for Alpine based image, see [project](https://gitea.zionetrix.net/bn8/check_apk) for install instructions
 
-__Note:__ The first plugin detected as installed will be used.
+**Note:** The first plugin detected as installed will be used.
 
 ## Installation
 
diff --git a/check_container_upgrade b/check_container_upgrade
index b300f68..6f92a46 100755
--- a/check_container_upgrade
+++ b/check_container_upgrade
@@ -139,7 +139,7 @@ fi
 EXIT_CODE=0
 declare -A CONTAINER_STATUS_FILE
 declare -A CONTAINER_PID
-declare -A UPTODATE
+declare -A UP_TO_DATE
 declare -A ERRORS
 declare -A UNKNOWNS
 CHECKED_CONTAINERS=( )
@@ -232,7 +232,7 @@ do
 	rm -f ${CONTAINER_STATUS_FILE[$container]}
 	if [ $ex -eq 0 ]
 	then
-		UPTODATE+=( ["$container"]=$STATUS )
+		UP_TO_DATE+=( ["$container"]=$STATUS )
 	else
 		ERRORS+=( ["$container"]=$STATUS )
 		[ $ex -ge 3 ] && UNKNOWNS+=( "$container" )
@@ -266,7 +266,7 @@ debug "Not found containers (${#NOTFOUNDS[@]}): $( implode ", " "${NOTFOUNDS[@]}
 # Compute performance data
 let CONTAINER_COUNTS=${#CHECKED_CONTAINERS[@]}+${#NOTFOUNDS[@]}
 PERF_DATA=(
-	"uptodate_containers=${#UPTODATE[@]};;;0;$CONTAINER_COUNTS"
+	"uptodate_containers=${#UP_TO_DATE[@]};;;0;$CONTAINER_COUNTS"
 	"containers_with_errors=${#ERRORS[@]};1;;0;$CONTAINER_COUNTS"
 	"unknown_state_containers=${#UNKNOWNS[@]};;;0;$CONTAINER_COUNTS"
 )
@@ -274,7 +274,7 @@ PERF_DATA=(
 # Display check result message
 case $EXIT_CODE in
 	0)
-		echo -n "OK - All ${#UPTODATE[@]} container(s) are uptodate"
+		echo -n "OK - All ${#UP_TO_DATE[@]} container(s) are up-to-date"
 		;;
 	1)
 		echo -n "WARNING - ${#ERRORS[@]} container(s) need to be updated"
@@ -296,9 +296,9 @@ do
     echo ${container} - ${ERRORS[${container}]}
 done
 
-for container in ${!UPTODATE[@]}
+for container in ${!UP_TO_DATE[@]}
 do
-    echo ${container} - ${UPTODATE[${container}]}
+    echo ${container} - ${UP_TO_DATE[${container}]}
 done
 
 exit $EXIT_CODE