diff --git a/sh/main.sh b/sh/main.sh
index 99882a7..7921bce 100644
--- a/sh/main.sh
+++ b/sh/main.sh
@@ -51,7 +51,7 @@ main_source_directory() {
 	[ -d "${path}" ] ||
 		return 1
 	local cmd count module modules
-	modules="$(sh_source_find "${path}" "${SH_MAIN_NAME}")"
+	modules="$(sh_find_sh "${path}" "${SH_MAIN_NAME}")"
 	_sh_ifs_new
 	count=0
 	_sh_main_log "" \
@@ -74,12 +74,13 @@ main_source_directory() {
 
 # public
 
-sh_source_find() {
-	local root="${1}"
-	local file="${2}"
+sh_find_extension() {
+	local extension="${1}"
+	local root="${2}"
+	local file="${3}"
 	set -- \
 		"${root}" \
-		-name "*.sh" \
+		-name "*.${extension}" \
 		-type "f"
 	[ -n "${file}" ] &&
 		set -- "${@}" \
@@ -90,6 +91,10 @@ sh_source_find() {
 		sort
 }
 
+sh_find_sh() {
+	sh_find_extension "sh" "${@}"
+}
+
 sh_help() {
 	sh_log \
 		"sh_… = shell functions" \
diff --git a/sh/shellcheck.sh b/sh/shellcheck.sh
index d5ccb53..567568c 100644
--- a/sh/shellcheck.sh
+++ b/sh/shellcheck.sh
@@ -2,7 +2,7 @@ sh_shellcheck() {
 	local root="${1}"
 	local file module modules
 	file="$(mktemp)"
-	modules="$(sh_source_find "${root}")"
+	modules="$(sh_find_sh "${root}")"
 	_sh_ifs_new
 	for module in ${modules}; do
 		echo ". \"${root}/${module}\"" >>"${file}"