diff --git a/clean_files.txt b/clean_files.txt
index 3d588f30..30ac90c6 100644
--- a/clean_files.txt
+++ b/clean_files.txt
@@ -63,6 +63,7 @@ plugins/available/xterm.plugin.bash
 completion/available/awless.completion.bash
 completion/available/brew.completion.bash
 completion/available/cargo.completion.bash
+completion/available/composer.completion.bash
 completion/available/conda.completion.bash
 completion/available/consul.completion.bash
 completion/available/docker.completion.bash
diff --git a/completion/available/composer.completion.bash b/completion/available/composer.completion.bash
index be19fd27..eefe50fa 100644
--- a/completion/available/composer.completion.bash
+++ b/completion/available/composer.completion.bash
@@ -1,133 +1,129 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+cite "about-completion"
+about-completion "composer completion"
 
-_composer()
-{
-    local cur script coms opts com
-    COMPREPLY=()
-    _get_comp_words_by_ref -n : cur words
+function __composer_completion() {
+	local cur coms opts com
+	COMPREPLY=()
+	_get_comp_words_by_ref -n : cur words
 
-    # for an alias, get the real script behind it
-    if [[ $(type -t ${words[0]}) == "alias" ]]; then
-        script=$(alias ${words[0]} | sed -E "s/alias ${words[0]}='(.*)'/\1/")
-    else
-        script=${words[0]}
-    fi
+	# lookup for command
+	for word in "${words[@]:1}"; do
+		if [[ $word != -* ]]; then
+			com=$word
+			break
+		fi
+	done
 
-    # lookup for command
-    for word in ${words[@]:1}; do
-        if [[ $word != -* ]]; then
-            com=$word
-            break
-        fi
-    done
+	# completing for an option
+	if [[ ${cur} == --* ]]; then
+		opts="--help --quiet --verbose --version --ansi --no-ansi --no-interaction --profile --no-plugins --working-dir"
 
-    # completing for an option
-    if [[ ${cur} == --* ]] ; then
-        opts="--help --quiet --verbose --version --ansi --no-ansi --no-interaction --profile --no-plugins --working-dir"
+		case "$com" in
+			about)
+				opts="${opts} "
+				;;
+			archive)
+				opts="${opts} --format --dir --file"
+				;;
+			browse)
+				opts="${opts} --homepage --show"
+				;;
+			clear-cache)
+				opts="${opts} "
+				;;
+			config)
+				opts="${opts} --global --editor --auth --unset --list --file --absolute"
+				;;
+			create-project)
+				opts="${opts} --stability --prefer-source --prefer-dist --repository --repository-url --dev --no-dev --no-custom-installers --no-scripts --no-progress --no-secure-http --keep-vcs --no-install --ignore-platform-reqs"
+				;;
+			depends)
+				opts="${opts} --recursive --tree"
+				;;
+			diagnose)
+				opts="${opts} "
+				;;
+			dump-autoload)
+				opts="${opts} --no-scripts --optimize --classmap-authoritative --apcu --no-dev"
+				;;
+			exec)
+				opts="${opts} --list"
+				;;
+			global)
+				opts="${opts} "
+				;;
+			help)
+				opts="${opts} --xml --format --raw"
+				;;
+			init)
+				opts="${opts} --name --description --author --type --homepage --require --require-dev --stability --license --repository"
+				;;
+			install)
+				opts="${opts} --prefer-source --prefer-dist --dry-run --dev --no-dev --no-custom-installers --no-autoloader --no-scripts --no-progress --no-suggest --optimize-autoloader --classmap-authoritative --apcu-autoloader --ignore-platform-reqs"
+				;;
+			licenses)
+				opts="${opts} --format --no-dev"
+				;;
+			list)
+				opts="${opts} --xml --raw --format"
+				;;
+			outdated)
+				opts="${opts} --outdated --all --direct --strict"
+				;;
+			prohibits)
+				opts="${opts} --recursive --tree"
+				;;
+			remove)
+				opts="${opts} --dev --no-progress --no-update --no-scripts --update-no-dev --update-with-dependencies --no-update-with-dependencies --ignore-platform-reqs --optimize-autoloader --classmap-authoritative --apcu-autoloader"
+				;;
+			require)
+				opts="${opts} --dev --prefer-source --prefer-dist --no-progress --no-suggest --no-update --no-scripts --update-no-dev --update-with-dependencies --ignore-platform-reqs --prefer-stable --prefer-lowest --sort-packages --optimize-autoloader --classmap-authoritative --apcu-autoloader"
+				;;
+			run-script)
+				opts="${opts} --timeout --dev --no-dev --list"
+				;;
+			search)
+				opts="${opts} --only-name --type"
+				;;
+			self-update)
+				opts="${opts} --rollback --clean-backups --no-progress --update-keys --stable --preview --snapshot"
+				;;
+			show)
+				opts="${opts} --all --installed --platform --available --self --name-only --path --tree --latest --outdated --minor-only --direct --strict"
+				;;
+			status)
+				opts="${opts} "
+				;;
+			suggests)
+				opts="${opts} --by-package --by-suggestion --no-dev"
+				;;
+			update)
+				opts="${opts} --prefer-source --prefer-dist --dry-run --dev --no-dev --lock --no-custom-installers --no-autoloader --no-scripts --no-progress --no-suggest --with-dependencies --optimize-autoloader --classmap-authoritative --apcu-autoloader --ignore-platform-reqs --prefer-stable --prefer-lowest --interactive --root-reqs"
+				;;
+			validate)
+				opts="${opts} --no-check-all --no-check-lock --no-check-publish --with-dependencies --strict"
+				;;
 
-        case "$com" in
-            about)
-            opts="${opts} "
-            ;;
-            archive)
-            opts="${opts} --format --dir --file"
-            ;;
-            browse)
-            opts="${opts} --homepage --show"
-            ;;
-            clear-cache)
-            opts="${opts} "
-            ;;
-            config)
-            opts="${opts} --global --editor --auth --unset --list --file --absolute"
-            ;;
-            create-project)
-            opts="${opts} --stability --prefer-source --prefer-dist --repository --repository-url --dev --no-dev --no-custom-installers --no-scripts --no-progress --no-secure-http --keep-vcs --no-install --ignore-platform-reqs"
-            ;;
-            depends)
-            opts="${opts} --recursive --tree"
-            ;;
-            diagnose)
-            opts="${opts} "
-            ;;
-            dump-autoload)
-            opts="${opts} --no-scripts --optimize --classmap-authoritative --apcu --no-dev"
-            ;;
-            exec)
-            opts="${opts} --list"
-            ;;
-            global)
-            opts="${opts} "
-            ;;
-            help)
-            opts="${opts} --xml --format --raw"
-            ;;
-            init)
-            opts="${opts} --name --description --author --type --homepage --require --require-dev --stability --license --repository"
-            ;;
-            install)
-            opts="${opts} --prefer-source --prefer-dist --dry-run --dev --no-dev --no-custom-installers --no-autoloader --no-scripts --no-progress --no-suggest --optimize-autoloader --classmap-authoritative --apcu-autoloader --ignore-platform-reqs"
-            ;;
-            licenses)
-            opts="${opts} --format --no-dev"
-            ;;
-            list)
-            opts="${opts} --xml --raw --format"
-            ;;
-            outdated)
-            opts="${opts} --outdated --all --direct --strict"
-            ;;
-            prohibits)
-            opts="${opts} --recursive --tree"
-            ;;
-            remove)
-            opts="${opts} --dev --no-progress --no-update --no-scripts --update-no-dev --update-with-dependencies --no-update-with-dependencies --ignore-platform-reqs --optimize-autoloader --classmap-authoritative --apcu-autoloader"
-            ;;
-            require)
-            opts="${opts} --dev --prefer-source --prefer-dist --no-progress --no-suggest --no-update --no-scripts --update-no-dev --update-with-dependencies --ignore-platform-reqs --prefer-stable --prefer-lowest --sort-packages --optimize-autoloader --classmap-authoritative --apcu-autoloader"
-            ;;
-            run-script)
-            opts="${opts} --timeout --dev --no-dev --list"
-            ;;
-            search)
-            opts="${opts} --only-name --type"
-            ;;
-            self-update)
-            opts="${opts} --rollback --clean-backups --no-progress --update-keys --stable --preview --snapshot"
-            ;;
-            show)
-            opts="${opts} --all --installed --platform --available --self --name-only --path --tree --latest --outdated --minor-only --direct --strict"
-            ;;
-            status)
-            opts="${opts} "
-            ;;
-            suggests)
-            opts="${opts} --by-package --by-suggestion --no-dev"
-            ;;
-            update)
-            opts="${opts} --prefer-source --prefer-dist --dry-run --dev --no-dev --lock --no-custom-installers --no-autoloader --no-scripts --no-progress --no-suggest --with-dependencies --optimize-autoloader --classmap-authoritative --apcu-autoloader --ignore-platform-reqs --prefer-stable --prefer-lowest --interactive --root-reqs"
-            ;;
-            validate)
-            opts="${opts} --no-check-all --no-check-lock --no-check-publish --with-dependencies --strict"
-            ;;
+		esac
 
-        esac
+		# shellcheck disable=SC2207
+		COMPREPLY=($(compgen -W "${opts}" -- "${cur}"))
+		__ltrim_colon_completions "$cur"
 
-        COMPREPLY=($(compgen -W "${opts}" -- ${cur}))
-        __ltrim_colon_completions "$cur"
+		return 0
+	fi
 
-        return 0;
-    fi
+	# completing for a command
+	if [[ "$cur" == "$com" ]]; then
+		coms="about archive browse clear-cache config create-project depends diagnose dump-autoload exec global help init install licenses list outdated prohibits remove require run-script search self-update show status suggests update validate"
 
-    # completing for a command
-    if [[ $cur == $com ]]; then
-        coms="about archive browse clear-cache config create-project depends diagnose dump-autoload exec global help init install licenses list outdated prohibits remove require run-script search self-update show status suggests update validate"
+		# shellcheck disable=SC2207
+		COMPREPLY=($(compgen -W "${coms}" -- "${cur}"))
+		__ltrim_colon_completions "$cur"
 
-        COMPREPLY=($(compgen -W "${coms}" -- ${cur}))
-        __ltrim_colon_completions "$cur"
-
-        return 0
-    fi
+		return 0
+	fi
 }
 
-complete -o default -F _composer composer
+complete -o default -F __composer_completion composer