diff --git a/clean_files.txt b/clean_files.txt
index 203d1caa42..bfc5596144 100644
--- a/clean_files.txt
+++ b/clean_files.txt
@@ -41,7 +41,6 @@ themes/atomic
 themes/axin
 themes/bakke
 themes/barbuk
-themes/base.theme.bash
 themes/binaryanomaly
 themes/bira
 themes/bobby
@@ -53,6 +52,8 @@ themes/clean
 themes/codeword
 themes/cooperkid
 themes/cupcake
+themes/demula
+themes/dos
 themes/doubletime
 themes/doubletime_multiline
 themes/doubletime_multiline_pyonly
@@ -60,12 +61,19 @@ themes/dulcie
 themes/duru
 themes/easy
 themes/elixr
+themes/emperor
+themes/envy
 themes/essential
-themes/githelpers.theme.bash
+themes/font
+themes/gallifrey
 themes/gitline
+themes/hawaii50
 themes/inretio
+themes/iterate
+themes/kitsune
 themes/lambda
 themes/liquidprompt
+themes/luan
 themes/modern
 themes/norbu
 themes/oh-my-posh
diff --git a/themes/agnoster/agnoster.theme.bash b/themes/agnoster/agnoster.theme.bash
index d5bac5ca69..c274058994 100644
--- a/themes/agnoster/agnoster.theme.bash
+++ b/themes/agnoster/agnoster.theme.bash
@@ -235,7 +235,8 @@ prompt_histdt() {
 }
 
 git_status_dirty() {
-	dirty=$(git status -s 2> /dev/null | tail -n 1)
+	local dirty
+	dirty=$(git status --porcelain 2> /dev/null | tail -n 1)
 	[[ -n $dirty ]] && echo " ●"
 }
 
diff --git a/themes/demula/demula.theme.bash b/themes/demula/demula.theme.bash
index f20e6097aa..4bf2e1efd7 100644
--- a/themes/demula/demula.theme.bash
+++ b/themes/demula/demula.theme.bash
@@ -1,4 +1,5 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
 
 # Theme inspired on:
 #  - Ronacher's dotfiles (mitsuhikos) - http://github.com/mitsuhiko/dotfiles/tree/master/bash/
@@ -10,40 +11,40 @@
 # Screenshot: http://goo.gl/VCmX5
 # by Jesus de Mula <jesus@demula.name>
 
-# For the real Monokai colors you should add these to your .XDefaults or
-# terminal configuration:
-#! ----------------------------------------------------------- TERMINAL COLORS
-#! monokai - http://www.monokai.nl/blog/2006/07/15/textmate-color-theme/
-#*background: #272822
-#*foreground: #E2DA6E
-#*color0: black
-#! mild red
-#*color1: #CD0000
-#! light green
-#*color2: #A5E02D
-#! orange (yellow)
-#*color3: #FB951F
-#! "dark" blue
-#*color4: #076BCC
-#! hot pink
-#*color5: #F6266C
-#! cyan
-#*color6: #64D9ED
-#! gray
-#*color7: #E5E5E5
+## For the real Monokai colors you should add these to your .XDefaults or
+## terminal configuration:
+## ! ----------------------------------------------------------- TERMINAL COLORS
+## ! monokai - http://www.monokai.nl/blog/2006/07/15/textmate-color-theme/
+## *background: #272822
+## *foreground: #E2DA6E
+## *color0: black
+## ! mild red
+## *color1: #CD0000
+## ! light green
+## *color2: #A5E02D
+## ! orange (yellow)
+## *color3: #FB951F
+## ! "dark" blue
+## *color4: #076BCC
+## ! hot pink
+## *color5: #F6266C
+## ! cyan
+## *color6: #64D9ED
+## ! gray
+## *color7: #E5E5E5
 
 # ----------------------------------------------------------------- COLOR CONF
-D_DEFAULT_COLOR="${normal}"
-D_INTERMEDIATE_COLOR="${white}"
-D_USER_COLOR="${purple}"
-D_SUPERUSER_COLOR="${red}"
-D_MACHINE_COLOR="${cyan}"
-D_DIR_COLOR="${green}"
-D_SCM_COLOR="${yellow}"
-D_BRANCH_COLOR="${yellow}"
-D_CHANGES_COLOR="${white}"
-D_CMDFAIL_COLOR="${red}"
-D_VIMSHELL_COLOR="${cyan}"
+D_DEFAULT_COLOR="${normal?}"
+D_INTERMEDIATE_COLOR="${white?}"
+D_USER_COLOR="${purple?}"
+D_SUPERUSER_COLOR="${red?}"
+D_MACHINE_COLOR="${cyan?}"
+D_DIR_COLOR="${green?}"
+D_SCM_COLOR="${yellow?}"
+D_BRANCH_COLOR="${yellow?}"
+D_CHANGES_COLOR="${white?}"
+D_CMDFAIL_COLOR="${red?}"
+D_VIMSHELL_COLOR="${cyan?}"
 
 # ------------------------------------------------------------------ FUNCTIONS
 case $TERM in
@@ -56,7 +57,7 @@ case $TERM in
 esac
 
 is_vim_shell() {
-	if [ ! -z "$VIMRUNTIME" ]; then
+	if [ -n "$VIMRUNTIME" ]; then
 		echo "${D_INTERMEDIATE_COLOR}on ${D_VIMSHELL_COLOR}\
 vim shell${D_DEFAULT_COLOR} "
 	fi
@@ -72,7 +73,7 @@ $code ${D_DEFAULT_COLOR}"
 
 # vcprompt for scm instead of bash_it default
 demula_vcprompt() {
-	if [ ! -z "$VCPROMPT_EXECUTABLE" ]; then
+	if [ -n "$VCPROMPT_EXECUTABLE" ]; then
 		local D_VCPROMPT_FORMAT="on ${D_SCM_COLOR}%s${D_INTERMEDIATE_COLOR}:\
 ${D_BRANCH_COLOR}%b %r ${D_CHANGES_COLOR}%m%u ${D_DEFAULT_COLOR}"
 		$VCPROMPT_EXECUTABLE -f "$D_VCPROMPT_FORMAT"
@@ -88,7 +89,8 @@ safe_battery_charge() {
 
 # -------------------------------------------------------------- PROMPT OUTPUT
 prompt() {
-	local LAST_COMMAND_FAILED=$(mitsuhikos_lastcommandfailed)
+	local LAST_COMMAND_FAILED
+	LAST_COMMAND_FAILED=$(mitsuhikos_lastcommandfailed)
 	local SAVE_CURSOR='\033[s'
 	local RESTORE_CURSOR='\033[u'
 	local MOVE_CURSOR_RIGHTMOST='\033[500C'
diff --git a/themes/dos/dos.theme.bash b/themes/dos/dos.theme.bash
index 17f0cff646..d7e072c2e9 100644
--- a/themes/dos/dos.theme.bash
+++ b/themes/dos/dos.theme.bash
@@ -1 +1,3 @@
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
 PROMPT="\w>>"
diff --git a/themes/emperor/emperor.theme.bash b/themes/emperor/emperor.theme.bash
index 2f02eca78a..da145fcd6f 100644
--- a/themes/emperor/emperor.theme.bash
+++ b/themes/emperor/emperor.theme.bash
@@ -1,29 +1,30 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
 
-SCM_THEME_PROMPT_DIRTY=" ${red}✗"
-SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓"
+SCM_THEME_PROMPT_DIRTY=" ${red?}✗"
+SCM_THEME_PROMPT_CLEAN=" ${bold_green?}✓"
 SCM_THEME_PROMPT_PREFIX=" |"
-SCM_THEME_PROMPT_SUFFIX="${green}|"
+SCM_THEME_PROMPT_SUFFIX="${green?}|"
 
-GIT_THEME_PROMPT_DIRTY=" ${red}✗"
-GIT_THEME_PROMPT_CLEAN=" ${bold_green}✓"
-GIT_THEME_PROMPT_PREFIX=" ${green}|"
-GIT_THEME_PROMPT_SUFFIX="${green}|"
+GIT_THEME_PROMPT_DIRTY=" ${red?}✗"
+GIT_THEME_PROMPT_CLEAN=" ${bold_green?}✓"
+GIT_THEME_PROMPT_PREFIX=" ${green?}|"
+GIT_THEME_PROMPT_SUFFIX="${green?}|"
 
 RVM_THEME_PROMPT_PREFIX="|"
 RVM_THEME_PROMPT_SUFFIX="|"
 
 function get_hour_color {
-	hour_color=$red
+	hour_color=${red?}
 	min=$(date +%M)
 	if [ "$min" -lt "15" ]; then
-		hour_color=$white
+		hour_color=${white?}
 	elif [ "$min" -lt "30" ]; then
-		hour_color=$green
+		hour_color=${green?}
 	elif [ "$min" -lt "45" ]; then
-		hour_color=$yellow
+		hour_color=${yellow?}
 	else
-		hour_color=$red
+		hour_color=${red?}
 	fi
 	echo "$hour_color"
 }
@@ -34,7 +35,7 @@ __emperor_clock() {
 }
 
 function prompt_command() {
-	PS1="\n$(__emperor_clock)${purple}\h ${reset_color}in ${prompt_color}\w\n${bold_cyan}$(scm_char)${green}$(scm_prompt_info) ${green}→${reset_color} "
+	PS1="\n$(__emperor_clock)${purple?}\h ${reset_color?}in ${prompt_color?}\w\n${bold_cyan?}$(scm_char)${green?}$(scm_prompt_info) ${green?}→${reset_color?} "
 }
 
 THEME_CLOCK_FORMAT=${THEME_CLOCK_FORMAT:-"%H "}
diff --git a/themes/envy/envy.theme.bash b/themes/envy/envy.theme.bash
index ae28c1f622..acb0136fb9 100644
--- a/themes/envy/envy.theme.bash
+++ b/themes/envy/envy.theme.bash
@@ -1,19 +1,21 @@
-#!/usr/bin/env bash
-SCM_THEME_PROMPT_DIRTY=" ${red}✗"
-SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓"
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+
+SCM_THEME_PROMPT_DIRTY=" ${red?}✗"
+SCM_THEME_PROMPT_CLEAN=" ${bold_green?}✓"
 SCM_THEME_PROMPT_PREFIX=" |"
-SCM_THEME_PROMPT_SUFFIX="${green}|"
+SCM_THEME_PROMPT_SUFFIX="${green?}|"
 
-GIT_THEME_PROMPT_DIRTY=" ${red}✗"
-GIT_THEME_PROMPT_CLEAN=" ${bold_green}✓"
-GIT_THEME_PROMPT_PREFIX=" ${green}|"
-GIT_THEME_PROMPT_SUFFIX="${green}|"
+GIT_THEME_PROMPT_DIRTY=" ${red?}✗"
+GIT_THEME_PROMPT_CLEAN=" ${bold_green?}✓"
+GIT_THEME_PROMPT_PREFIX=" ${green?}|"
+GIT_THEME_PROMPT_SUFFIX="${green?}|"
 
-VIRTUALENV_THEME_PROMPT_PREFIX="${green}ⓔ  "
+VIRTUALENV_THEME_PROMPT_PREFIX="${green?}ⓔ  "
 VIRTUALENV_THEME_PROMPT_SUFFIX=""
 
 function prompt_command() {
-	PS1="\n$(virtualenv_prompt)${yellow}$(ruby_version_prompt) ${purple}\h ${reset_color}in ${green}\w\n${bold_cyan}$(scm_char)${green}$(scm_prompt_info) ${green}→${reset_color} "
+	PS1="\n$(virtualenv_prompt)${yellow?}$(ruby_version_prompt) ${purple?}\h ${reset_color?}in ${green?}\w\n${bold_cyan?}$(scm_char)${green?}$(scm_prompt_info) ${green?}→${reset_color?} "
 }
 
 safe_append_prompt_command prompt_command
diff --git a/themes/font/font.theme.bash b/themes/font/font.theme.bash
index 5af5e0e013..bf010b7352 100644
--- a/themes/font/font.theme.bash
+++ b/themes/font/font.theme.bash
@@ -1,4 +1,5 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
 #
 # One line prompt showing the following configurable information
 # for git:
@@ -22,20 +23,20 @@
 #
 
 SCM_NONE_CHAR=''
-SCM_THEME_PROMPT_DIRTY=" ${red}✗"
+SCM_THEME_PROMPT_DIRTY=" ${red?}✗"
 SCM_THEME_PROMPT_CLEAN=""
-SCM_THEME_PROMPT_PREFIX="${green}|"
-SCM_THEME_PROMPT_SUFFIX="${green}|"
+SCM_THEME_PROMPT_PREFIX="${green?}|"
+SCM_THEME_PROMPT_SUFFIX="${green?}|"
 SCM_GIT_SHOW_MINIMAL_INFO=true
 
 CLOCK_THEME_PROMPT_PREFIX=''
 CLOCK_THEME_PROMPT_SUFFIX=' '
 THEME_SHOW_CLOCK=false
-THEME_CLOCK_COLOR=${THEME_CLOCK_COLOR:-"$bold_blue"}
+THEME_CLOCK_COLOR=${THEME_CLOCK_COLOR:-"${bold_blue?}"}
 THEME_CLOCK_FORMAT=${THEME_CLOCK_FORMAT:-"%I:%M:%S"}
 
 THEME_SHOW_USER_HOST=true
-USER_HOST_THEME_PROMPT_PREFIX="${bold_black}"
+USER_HOST_THEME_PROMPT_PREFIX="${bold_black?}"
 USER_HOST_THEME_PROMPT_SUFFIX=" "
 
 VIRTUALENV_THEME_PROMPT_PREFIX='('
@@ -45,20 +46,20 @@ function prompt_command() {
 	# This needs to be first to save last command return code
 	local RC="$?"
 
-	hostname="${bold_black}\u@\h"
-	virtualenv="${white}$(virtualenv_prompt)"
+	hostname="${bold_black?}\u@\h"
+	virtualenv="${white?}$(virtualenv_prompt)"
 
 	# Set return status color
 	if [[ ${RC} == 0 ]]; then
-		ret_status="${bold_green}"
+		ret_status="${bold_green?}"
 	else
-		ret_status="${bold_red}"
+		ret_status="${bold_red?}"
 	fi
 
 	# Append new history lines to history file
 	history -a
 
-	PS1="$(clock_prompt)${virtualenv}$(user_host_prompt)${bold_cyan}\W $(scm_prompt_char_info)${ret_status}→ ${normal}"
+	PS1="$(clock_prompt)${virtualenv}$(user_host_prompt)${bold_cyan?}\W $(scm_prompt_char_info)${ret_status}→ ${normal?}"
 }
 
 safe_append_prompt_command prompt_command
diff --git a/themes/gallifrey/gallifrey.theme.bash b/themes/gallifrey/gallifrey.theme.bash
index cbffc78c46..2a529bede3 100644
--- a/themes/gallifrey/gallifrey.theme.bash
+++ b/themes/gallifrey/gallifrey.theme.bash
@@ -1,12 +1,14 @@
-# scm theming
-SCM_THEME_PROMPT_PREFIX="${yellow}("
-SCM_THEME_PROMPT_SUFFIX=")${normal}"
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+
+SCM_THEME_PROMPT_PREFIX="${yellow?}("
+SCM_THEME_PROMPT_SUFFIX=")${normal?}"
 
 SCM_THEME_PROMPT_DIRTY="*"
 SCM_THEME_PROMPT_CLEAN=""
-SCM_GIT_CHAR="${green}±${normal}"
-SCM_SVN_CHAR="${bold_cyan}⑆${normal}"
-SCM_HG_CHAR="${bold_red}☿${normal}"
+SCM_GIT_CHAR="${green?}±${normal?}"
+SCM_SVN_CHAR="${bold_cyan?}⑆${normal?}"
+SCM_HG_CHAR="${bold_red?}☿${normal?}"
 
 ### TODO: openSUSE has already colors enabled, check if those differs from stock
 # LS colors, made with http://geoff.greer.fm/lscolors/
@@ -16,10 +18,10 @@ SCM_HG_CHAR="${bold_red}☿${normal}"
 gallifrey_prompt() {
 	SCM_PROMPT_FORMAT='%s%s'
 
-	ps_host="${green}\h${normal}"
-	ps_user_mark="${bold}\$${normal}"
-	ps_root_mark="${normal}§"
-	ps_path="${normal}\w"
+	ps_host="${green?}\h${normal?}"
+	ps_user_mark="${bold?}\$${normal?}"
+	ps_root_mark="${normal?}§"
+	ps_path="${normal?}\w"
 
 	# make it work
 	case $(id -u) in
diff --git a/themes/hawaii50/hawaii50.theme.bash b/themes/hawaii50/hawaii50.theme.bash
index 6cba1553fd..25ad6a6a13 100644
--- a/themes/hawaii50/hawaii50.theme.bash
+++ b/themes/hawaii50/hawaii50.theme.bash
@@ -1,4 +1,5 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
 #
 # This theme was obviously inspired a lot by
 #
@@ -42,22 +43,22 @@ VIRTUAL_PROMPT_ENABLED=1
 # COLORS ======================================================================
 ORANGE='\[\e[0;33m\]'
 
-DEFAULT_COLOR="${white}"
+DEFAULT_COLOR="${white?}"
 
-USER_COLOR="${purple}"
-SUPERUSER_COLOR="${red}"
+USER_COLOR="${purple?}"
+SUPERUSER_COLOR="${red?}"
 MACHINE_COLOR=$ORANGE
 IP_COLOR=$ORANGE
-DIRECTORY_COLOR="${green}"
+DIRECTORY_COLOR="${green?}"
 
-VE_COLOR="${cyan}"
-RVM_COLOR="${cyan}"
+VE_COLOR="${cyan?}"
+RVM_COLOR="${cyan?}"
 
-REF_COLOR="${purple}"
+REF_COLOR="${purple?}"
 
 # SCM prompts
-SCM_THEME_PROMPT_DIRTY=" ${bold_red}✗${normal}"
-SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓${normal}"
+SCM_THEME_PROMPT_DIRTY=" ${bold_red?}✗${normal?}"
+SCM_THEME_PROMPT_CLEAN=" ${bold_green?}✓${normal?}"
 SCM_THEME_PROMPT_PREFIX=' on '
 SCM_THEME_PROMPT_SUFFIX=''
 
@@ -85,7 +86,7 @@ IP_SEPARATOR=', '
 
 function get_ip_info {
 	myip=$(curl -s checkip.dyndns.org | grep -Eo '[0-9\.]+')
-	echo -e "$(ips | sed -e :a -e '$!N;s/\n/${IP_SEPARATOR}/;ta' | sed -e 's/127\.0\.0\.1\${IP_SEPARATOR}//g'), ${myip}"
+	echo -e "$(ips | sed -e :a -e "\$!N;s/\\n/${IP_SEPARATOR}/;ta" | sed -e "s/127\\.0\\.0\\.1\\${IP_SEPARATOR}//g"), ${myip}"
 }
 
 # Displays ip prompt
@@ -97,9 +98,10 @@ function ip_prompt_info() {
 
 # Displays virtual info prompt (virtualenv/rvm)
 function virtual_prompt_info() {
-	local virtual_env_info=$(virtualenv_prompt)
-	local rvm_info=$(ruby_version_prompt)
-	local virtual_prompt=""
+	local virtual_env_info rvm_info virtual_prompt
+	virtual_env_info=$(virtualenv_prompt)
+	rvm_info=$(ruby_version_prompt)
+	virtual_prompt=""
 
 	local prefix=${VIRTUAL_THEME_PROMPT_PREFIX}
 	local suffix=${VIRTUAL_THEME_PROMPT_SUFFIX}
@@ -119,7 +121,10 @@ function virtual_prompt_info() {
 
 # Parse git info
 function git_prompt_info() {
-	if [[ -n $(git status -s 2> /dev/null | grep -v ^# | grep -v "working directory clean") ]]; then
+	local dirty
+	dirty=$(git status --porcelain 2> /dev/null | tail -n 1)
+
+	if [[ -n $dirty ]]; then
 		state=${GIT_THEME_PROMPT_DIRTY:-$SCM_THEME_PROMPT_DIRTY}
 	else
 		state=${GIT_THEME_PROMPT_CLEAN:-$SCM_THEME_PROMPT_CLEAN}
@@ -170,7 +175,7 @@ function limited_pwd() {
 	# Replace $HOME with ~ if possible
 	RELATIVE_PWD=${PWD/#$HOME/\~}
 
-	local offset=$((${#RELATIVE_PWD} - $MAX_PWD_LENGTH))
+	local offset=$((${#RELATIVE_PWD} - MAX_PWD_LENGTH))
 
 	if [ $offset -gt "0" ]; then
 		local truncated_symbol="..."
@@ -187,9 +192,9 @@ function prompt() {
 	[ $UID -eq "0" ] && UC=$SUPERUSER_COLOR
 
 	if [[ $VIRTUAL_PROMPT_ENABLED == 1 ]]; then
-		PS1="$(scm_char) ${UC}\u ${DEFAULT_COLOR}at ${MACHINE_COLOR}\h$(ip_prompt_info) ${DEFAULT_COLOR}in ${DIRECTORY_COLOR}$(limited_pwd)${DEFAULT_COLOR}$(virtual_prompt_info)$(scm_prompt_info)${reset_color} \$ "
+		PS1="$(scm_char) ${UC}\u ${DEFAULT_COLOR}at ${MACHINE_COLOR}\h$(ip_prompt_info) ${DEFAULT_COLOR}in ${DIRECTORY_COLOR}$(limited_pwd)${DEFAULT_COLOR}$(virtual_prompt_info)$(scm_prompt_info)${reset_color?} \$ "
 	else
-		PS1="$(scm_char) ${UC}\u ${DEFAULT_COLOR}at ${MACHINE_COLOR}\h$(ip_prompt_info) ${DEFAULT_COLOR}in ${DIRECTORY_COLOR}$(limited_pwd)${DEFAULT_COLOR}$(scm_prompt_info)${reset_color} \$ "
+		PS1="$(scm_char) ${UC}\u ${DEFAULT_COLOR}at ${MACHINE_COLOR}\h$(ip_prompt_info) ${DEFAULT_COLOR}in ${DIRECTORY_COLOR}$(limited_pwd)${DEFAULT_COLOR}$(scm_prompt_info)${reset_color?} \$ "
 	fi
 	PS2='> '
 	PS4='+ '
diff --git a/themes/iterate/iterate.theme.bash b/themes/iterate/iterate.theme.bash
index 139d28c05c..009accb1cb 100644
--- a/themes/iterate/iterate.theme.bash
+++ b/themes/iterate/iterate.theme.bash
@@ -1,19 +1,21 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+
 SCM_GIT_CHAR="± "
 SCM_HG_CHAR="☿ "
 SCM_SVN_CHAR="⑆ "
 SCM_NONE_CHAR=""
-SCM_THEME_PROMPT_DIRTY=" ${red}✗"
-SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓"
+SCM_THEME_PROMPT_DIRTY=" ${red?}✗"
+SCM_THEME_PROMPT_CLEAN=" ${bold_green?}✓"
 SCM_THEME_PROMPT_PREFIX="|"
-SCM_THEME_PROMPT_SUFFIX="${green}| "
-SCM_GIT_AHEAD_CHAR="${green}+"
-SCM_GIT_BEHIND_CHAR="${red}-"
+SCM_THEME_PROMPT_SUFFIX="${green?}| "
+SCM_GIT_AHEAD_CHAR="${green?}+"
+SCM_GIT_BEHIND_CHAR="${red?}-"
 
-GIT_THEME_PROMPT_DIRTY=" ${bold_red}✗"
-GIT_THEME_PROMPT_CLEAN=" ${bold_green}✓"
-GIT_THEME_PROMPT_PREFIX="${cyan}|"
-GIT_THEME_PROMPT_SUFFIX="${cyan}| "
+GIT_THEME_PROMPT_DIRTY=" ${bold_red?}✗"
+GIT_THEME_PROMPT_CLEAN=" ${bold_green?}✓"
+GIT_THEME_PROMPT_PREFIX="${cyan?}|"
+GIT_THEME_PROMPT_SUFFIX="${cyan?}| "
 
 RVM_THEME_PROMPT_PREFIX="|"
 RVM_THEME_PROMPT_SUFFIX="| "
@@ -42,8 +44,9 @@ function git_prompt_info {
 
 LAST_PROMPT=""
 function prompt_command() {
-	local new_PS1="${bold_cyan}$(scm_char)${yellow}$(ruby_version_prompt)${green}\w $(scm_prompt_info)"
-	local new_prompt=$(PS1="$new_PS1" "$BASH" --norc -i < /dev/null 2>&1 | sed -n '${s/^\(.*\)exit$/\1/p;}')
+	local new_PS1 new_prompt
+	new_PS1="${bold_cyan?}$(scm_char)${yellow?}$(ruby_version_prompt)${green?}\w $(scm_prompt_info)"
+	new_prompt=$(PS1="$new_PS1" "$BASH" --norc -i < /dev/null 2>&1 | sed -n "\${s/^\(.*\)exit\$/\1/p;}")
 
 	if [ "$LAST_PROMPT" = "$new_prompt" ]; then
 		new_PS1=""
@@ -52,8 +55,8 @@ function prompt_command() {
 	fi
 
 	local wrap_char=""
-	[[ $COLUMNS && ${#new_PS1} > $(($COLUMNS / 1)) ]] && wrap_char="\n"
-	PS1="${new_PS1}${green}${wrap_char}→${reset_color} "
+	[[ $COLUMNS && ${#new_PS1} -gt COLUMNS ]] && wrap_char="\n"
+	PS1="${new_PS1}${green?}${wrap_char}→${reset_color?} "
 }
 
 safe_append_prompt_command prompt_command
diff --git a/themes/kitsune/kitsune.theme.bash b/themes/kitsune/kitsune.theme.bash
index 3f767ddf42..268d6e5012 100644
--- a/themes/kitsune/kitsune.theme.bash
+++ b/themes/kitsune/kitsune.theme.bash
@@ -1,3 +1,6 @@
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+
 # This is combination of works from two different people which I combined for my requirement.
 # Original PS1 was from reddit user /u/Allevil669 which I found in thread: https://www.reddit.com/r/linux/comments/1z33lj/linux_users_whats_your_favourite_bash_prompt/
 # I used that PS1 to the bash-it theme 'morris', and customized it to my liking. All credits to /u/Allevil669 and morris.
@@ -16,21 +19,22 @@ case $TERM in
 		TITLEBAR=""
 		;;
 esac
+# shellcheck disable=SC2181
 if [ "$?" == "0" ]; then
-	SC="${green}^_^"
+	SC="${green?}^_^"
 else
-	SC="${red}T_T"
+	SC="${red?}T_T"
 fi
 BC=$(battery_percentage)
 function prompt_command() {
 	#PS1="${TITLEBAR}[\u@\h \W $(scm_prompt_info)]\$ "
-	PS1="\n${cyan}┌─${bold_white}[\u@\h]${cyan}─${bold_yellow}(\w)$(scm_prompt_info)\n${cyan}└─${bold_green}[\A]-${green}($BC%)${bold_cyan}-[${green}${bold_green}\$${bold_cyan}]${green} "
+	PS1="\n${cyan?}┌─${bold_white?}[\u@\h]${cyan?}─${bold_yellow?}(\w)$(scm_prompt_info)\n${cyan?}└─${bold_green?}[\A]-${green?}($BC%)${bold_cyan?}-[${green?}${bold_green?}\$${bold_cyan?}]${green?} "
 }
 
 # scm theming
-SCM_THEME_PROMPT_DIRTY=" ${red}✗"
-SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓"
-SCM_THEME_PROMPT_PREFIX="${bold_cyan}("
-SCM_THEME_PROMPT_SUFFIX="${bold_cyan})${reset_color}"
+SCM_THEME_PROMPT_DIRTY=" ${red?}✗"
+SCM_THEME_PROMPT_CLEAN=" ${bold_green?}✓"
+SCM_THEME_PROMPT_PREFIX="${bold_cyan?}("
+SCM_THEME_PROMPT_SUFFIX="${bold_cyan?})${reset_color?}"
 
 safe_append_prompt_command prompt_command
diff --git a/themes/luan/luan.theme.bash b/themes/luan/luan.theme.bash
index d5f0331f44..9e0f167404 100644
--- a/themes/luan/luan.theme.bash
+++ b/themes/luan/luan.theme.bash
@@ -1,33 +1,34 @@
-#!/usr/bin/env bash
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
 
-SCM_THEME_PROMPT_DIRTY=" ${red}✗"
-SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓"
-SCM_THEME_PROMPT_PREFIX="(${yellow}"
-SCM_THEME_PROMPT_SUFFIX="${normal})"
+SCM_THEME_PROMPT_DIRTY=" ${red?}✗"
+SCM_THEME_PROMPT_CLEAN=" ${bold_green?}✓"
+SCM_THEME_PROMPT_PREFIX="(${yellow?}"
+SCM_THEME_PROMPT_SUFFIX="${normal?})"
 
-GIT_THEME_PROMPT_DIRTY=" ${red}✗"
-GIT_THEME_PROMPT_CLEAN=" ${bold_green}✓"
-GIT_THEME_PROMPT_PREFIX="(${yellow}"
-GIT_THEME_PROMPT_SUFFIX="${normal})"
+GIT_THEME_PROMPT_DIRTY=" ${red?}✗"
+GIT_THEME_PROMPT_CLEAN=" ${bold_green?}✓"
+GIT_THEME_PROMPT_PREFIX="(${yellow?}"
+GIT_THEME_PROMPT_SUFFIX="${normal?})"
 
 RVM_THEME_PROMPT_PREFIX=""
 RVM_THEME_PROMPT_SUFFIX=""
 
 function prompt_command() {
 	dtime="$(clock_prompt)"
-	user_host="${green}\u@${cyan}\h${normal}"
-	current_dir="${bold_blue}\w${normal}"
-	rvm_ruby="${bold_red}$(ruby_version_prompt)${normal}"
-	git_branch="$(scm_prompt_info)${normal}"
-	prompt="${bold_green}\$${normal} "
-	arrow="${bold_white}▶${normal} "
-	prompt="${bold_green}\$${normal} "
+	user_host="${green?}\u@${cyan?}\h${normal?}"
+	current_dir="${bold_blue?}\w${normal?}"
+	rvm_ruby="${bold_red?}$(ruby_version_prompt)${normal?}"
+	git_branch="$(scm_prompt_info)${normal?}"
+	prompt="${bold_green?}\$${normal?} "
+	arrow="${bold_white?}▶${normal?} "
+	prompt="${bold_green?}\$${normal?} "
 
 	PS1="${dtime}${user_host}:${current_dir} ${rvm_ruby} ${git_branch}
       $arrow $prompt"
 }
 
-THEME_CLOCK_COLOR=${THEME_CLOCK_COLOR:-"$yellow"}
+THEME_CLOCK_COLOR=${THEME_CLOCK_COLOR:-"${yellow?}"}
 THEME_CLOCK_FORMAT=${THEME_TIME_FORMAT:-"%I:%M:%S "}
 
 safe_append_prompt_command prompt_command