diff --git a/clean_files.txt b/clean_files.txt
index 758e3b80a7..29e0dd1d50 100644
--- a/clean_files.txt
+++ b/clean_files.txt
@@ -151,7 +151,6 @@ themes/atomic
 themes/axin
 themes/bakke
 themes/barbuk
-themes/base.theme.bash
 themes/binaryanomaly
 themes/bira
 themes/bobby
@@ -159,6 +158,7 @@ themes/bobby-python
 themes/brainy
 themes/brunton
 themes/candy
+themes/clean
 themes/easy
 themes/essential
 themes/githelpers.theme.bash
diff --git a/themes/clean/clean.theme.bash b/themes/clean/clean.theme.bash
index 0082d671a0..47a436b34d 100644
--- a/themes/clean/clean.theme.bash
+++ b/themes/clean/clean.theme.bash
@@ -1,19 +1,24 @@
+# shellcheck shell=bash
+# shellcheck disable=SC2034 # Expected behavior for themes.
+
 # git theming
-SCM_THEME_PROMPT_PREFIX="${bold_blue}(${yellow}"
-SCM_THEME_PROMPT_SUFFIX="${bold_blue})${reset_color} "
+SCM_THEME_PROMPT_PREFIX="${bold_blue?}(${yellow?}"
+SCM_THEME_PROMPT_SUFFIX="${bold_blue?})${reset_color?} "
 SCM_THEME_PROMPT_CLEAN=""
-SCM_THEME_PROMPT_DIRTY="${bold_red}✗"
-
+SCM_THEME_PROMPT_DIRTY="${bold_red?}✗"
 
 # LS colors, made with http://geoff.greer.fm/lscolors/
 export LSCOLORS="Gxfxcxdxbxegedabagacad"
 export LS_COLORS='no=00:fi=00:di=01;34:ln=00;36:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=41;33;01:ex=00;32:*.cmd=00;32:*.exe=01;32:*.com=01;32:*.bat=01;32:*.btm=01;32:*.dll=01;32:*.tar=00;31:*.tbz=00;31:*.tgz=00;31:*.rpm=00;31:*.deb=00;31:*.arj=00;31:*.taz=00;31:*.lzh=00;31:*.lzma=00;31:*.zip=00;31:*.zoo=00;31:*.z=00;31:*.Z=00;31:*.gz=00;31:*.bz2=00;31:*.tb2=00;31:*.tz2=00;31:*.tbz2=00;31:*.avi=01;35:*.bmp=01;35:*.fli=01;35:*.gif=01;35:*.jpg=01;35:*.jpeg=01;35:*.mng=01;35:*.mov=01;35:*.mpg=01;35:*.pcx=01;35:*.pbm=01;35:*.pgm=01;35:*.png=01;35:*.ppm=01;35:*.tga=01;35:*.tif=01;35:*.xbm=01;35:*.xpm=01;35:*.dl=01;35:*.gl=01;35:*.wmv=01;35:*.aiff=00;32:*.au=00;32:*.mid=00;32:*.mp3=00;32:*.ogg=00;32:*.voc=00;32:*.wav=00;32:'
 
 function prompt_command() {
+	if [ "$(whoami)" = root ]; then
+		no_color=${red?}
+	else
+		no_color=${white?}
+	fi
 
-    if [ "$(whoami)" = root ]; then no_color=$red; else no_color=$white; fi
-
-    PS1="${no_color}\u${reset_color}:${blue}\W/${reset_color} $(scm_prompt_info)${normal}$ "
+	PS1="${no_color}\u${reset_color}:${blue?}\W/${reset_color} $(scm_prompt_info)${normal?}$ "
 }
 
 safe_append_prompt_command prompt_command