diff --git a/bin/check.sh b/bin/check.sh
index 3e491ad0..05095523 100755
--- a/bin/check.sh
+++ b/bin/check.sh
@@ -87,7 +87,11 @@ _check_POSIX_files() {
       | grep -Eiqe '^#!/usr/bin/env sh' ;
     then
       _check_file "$1" || return 1
+    # We only care POSIX issue for files under `lib/`
+    elif echo "$1" | grep -qs "lib/"; then
+      >&2 echo ":: WARNING: POSIX help-wanted '$1'"
     fi
+
     shift
   done
 }
diff --git a/lib/dpkg.sh b/lib/dpkg.sh
index 48064fc2..83bdfb6a 100644
--- a/lib/dpkg.sh
+++ b/lib/dpkg.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env sh
 
 # Purpose: Debian / Ubuntu support
 # Author : Anh K. Huynh
@@ -20,11 +20,11 @@ _dpkg_init() {
 # dpkg_Q may _not_implemented
 # FIXME: Need to support a small list of packages
 dpkg_Q() {
-  if [[ "$_TOPT" == "q" ]]; then
+  if [ "$_TOPT" = "q" ]; then
     dpkg -l \
     | grep -E '^[hi]i' \
     | awk '{print $2}'
-  elif [[ "$_TOPT" == "" ]]; then
+  elif [ -z "$_TOPT" ]; then
     dpkg -l "$@" \
     | grep -E '^[hi]i'
   else
@@ -45,7 +45,7 @@ dpkg_Qe() {
 }
 
 dpkg_Ql() {
-  if [[ -n "$*" ]]; then
+  if [ $# -ge 1 ]; then
     dpkg-query -L "$@"
     return
   fi
@@ -54,7 +54,7 @@ dpkg_Ql() {
   | grep -E '^[hi]i' \
   | awk '{print $2}' \
   | while read -r _pkg; do
-      if [[ "$_TOPT" == "q" ]]; then
+      if [ "$_TOPT" = "q" ]; then
         dpkg-query -L "$_pkg"
       else
         dpkg-query -L "$_pkg" \
@@ -94,7 +94,7 @@ dpkg_Qs() {
 
 # dpkg_Rs may _not_implemented
 dpkg_Rs() {
-  if [[ "$_TOPT" == "" ]]; then
+  if [ -z "$_TOPT" ]; then
     apt-get autoremove "$@"
   else
     _not_implemented
@@ -140,19 +140,18 @@ dpkg_Sy() {
   apt-get update "$@"
 }
 
+# FIXME: A simple implemention for #53 and
+# FIXME: https://github.com/icy/pacapt/pull/156
+# FIXME: but I'm not sure there is any issue...
 dpkg_Ss() {
-  local IFS=$'\n'
-  packages=($(apt-cache search "$@"))
-  for package in ${packages[@]:-}
-  do
-    name=${package%% - *}
-    desc=${package#* - }
-    dpkg-query -W "$name" > /dev/null 2>&1
-    if [[ $? -eq 1 ]]; then
-      echo -e "package/$name \n    $desc"
-    else
-      dpkg-query -W -f='package/${binary:Package} ${Version}\t[${Status}]\n    ${binary:Summary}\n' "$name"
-    fi
+  apt-cache search "${@:-.}" \
+  | while read -r name _dash desc; do
+      if ! dpkg-query -W "$name" > /dev/null 2>&1; then
+        printf "package/%s \n    %s\n" \
+          "$name" "$desc"
+      else
+        dpkg-query -W -f='package/${binary:Package} ${Version}\n    ${binary:Summary}\n' "$name"
+      fi
   done
 }
 
@@ -165,6 +164,7 @@ dpkg_Scc() {
 }
 
 dpkg_S() {
+  # shellcheck disable=SC2086
   apt-get install $_TOPT "$@"
 }
 
diff --git a/lib/zz_main.sh b/lib/zz_main.sh
index e0e9fe82..3617886e 100644
--- a/lib/zz_main.sh
+++ b/lib/zz_main.sh
@@ -69,26 +69,13 @@ _PACMAN_detect \
 # Once we haven't switcher over `bash`, there is great chance
 # the current system are missing `Bash` ; on these systems
 # our library are not ready for pure-POSIX features!
-# FIXME: Now this list has to be updated manually.
 if [ -z "${__PACAPT_FORKED__:-}" ]; then
   case "$_PACMAN" in
-  "apk")  ;;
-  "conda")  ;;
-  "dnf") ;;
-  "homebrew") ;;
-  "macports") ;;
-  "opkg") ;;
-  "pkgng") ;;
-  "pkg_tools") ;;
-  "portage") ;;
-  "sun_tools" ) ;;
-  "swupd" ) ;;
-  "tazpkg") ;;
-  "tlmgr" ) ;;
-  "yum" ) ;;
-  "zypper" ) ;;
-  *)
+  "cave")
     _die "pacapt($_PACMAN) library is not ready for pure-POSIX features (or your Bash version is not >= 4)."
+    ;;
+  *)
+    ;;
   esac
 fi
 
diff --git a/tests/dpkg.txt b/tests/dpkg.txt
index 7b3e3e1f..94df8822 100644
--- a/tests/dpkg.txt
+++ b/tests/dpkg.txt
@@ -7,13 +7,15 @@
 # FIXME: debian:squeeze It's unable to run `pacman -Sy`
 im ubuntu:14.04 ubuntu:16.04  ubuntu:18.04   ubuntu:20.04  ubuntu
 im              debian:jessie debian:stretch debian:buster debian
+im debian_bash3
 
 # Remove `docker-clean` because we need *.deb files under /var/cache
 in ! rm -fv /etc/apt/apt.conf.d/docker-clean
 ou ^removed .*docker-clean
 
 in ! PACAPT_DEBUG=auto pacman
-ou debug.*Switching to Bash shell
+in ! if bash --version | grep -qs 'version 3'; then echo "Bash3-no-switching"; fi
+ou (debug.*Switching to Bash shell)|(Bash3-no-switching)
 
 in -P
 ou available operations:.*( [Q][ ilos])+
@@ -114,7 +116,8 @@ ou ^ Package: screen
 in -Sc
 in clear
 in -sS tmux
-ou tmux
+ou package/tmux
+ou terminal multiplexer
 
 # Strong cleaning up
 in -Sccc