diff --git a/themes/modern/modern.theme.bash b/themes/modern/modern.theme.bash
index eadb07624f..2aecb90016 100644
--- a/themes/modern/modern.theme.bash
+++ b/themes/modern/modern.theme.bash
@@ -1,17 +1,16 @@
 # shellcheck shell=bash
 # shellcheck disable=SC2034 # Expected behavior for themes.
-# shellcheck disable=SC2154 #TODO: fix these all.
 
 SCM_THEME_PROMPT_PREFIX=""
 SCM_THEME_PROMPT_SUFFIX=""
 
-SCM_THEME_PROMPT_DIRTY=" ${bold_red}✗${normal}"
-SCM_THEME_PROMPT_CLEAN=" ${bold_green}✓${normal}"
-SCM_GIT_CHAR="${bold_green}±${normal}"
-SCM_SVN_CHAR="${bold_cyan}⑆${normal}"
-SCM_HG_CHAR="${bold_red}☿${normal}"
+SCM_THEME_PROMPT_DIRTY=" ${bold_red?}✗${normal?}"
+SCM_THEME_PROMPT_CLEAN=" ${bold_green?}✓${normal?}"
+SCM_GIT_CHAR="${bold_green?}±${normal?}"
+SCM_SVN_CHAR="${bold_cyan?}⑆${normal?}"
+SCM_HG_CHAR="${bold_red?}☿${normal?}"
 
-case $TERM in
+case "${TERM:-dumb}" in
 	xterm*)
 		TITLEBAR="\[\033]0;\w\007\]"
 		;;
@@ -22,32 +21,34 @@ esac
 
 PS3=">> "
 
-is_vim_shell() {
-	if [ -n "$VIMRUNTIME" ]; then
-		echo "[${cyan}vim shell${normal}]"
+function is_vim_shell() {
+	if [[ -n "${VIMRUNTIME:-}" ]]; then
+		echo "[${cyan?}vim shell${normal?}]"
 	fi
 }
 
-detect_venv() {
-	python_venv=""
+function detect_venv() {
+	local python_venv=""
 	# Detect python venv
-	if [[ -n "${CONDA_DEFAULT_ENV}" ]]; then
-		python_venv="($PYTHON_VENV_CHAR${CONDA_DEFAULT_ENV}) "
-	elif [[ -n "${VIRTUAL_ENV}" ]]; then
-		python_venv="($PYTHON_VENV_CHAR$(basename "${VIRTUAL_ENV}")) "
+	if [[ -n "${CONDA_DEFAULT_ENV:-}" ]]; then
+		python_venv="(${PYTHON_VENV_CHAR}${CONDA_DEFAULT_ENV}) "
+	elif [[ -n "${VIRTUAL_ENV:-}" ]]; then
+		python_venv="(${PYTHON_VENV_CHAR}${VIRTUAL_ENV##*/}) "
 	fi
 }
 
-prompt() {
-	SCM_PROMPT_FORMAT='[%s][%s]'
-	retval=$?
+function prompt() {
+	local retval=$? scm_prompt is_vim_shell python_venv
+	local SCM_PROMPT_FORMAT='[%s][%s]'
+	scm_prompt="$(scm_prompt)"
+	is_vim_shell="$(is_vim_shell)"
 	if [[ retval -ne 0 ]]; then
-		PS1="${TITLEBAR}${bold_red}┌─${reset_color}$(scm_prompt)[${cyan}\u${normal}][${cyan}\w${normal}]$(is_vim_shell)\n${bold_red}└─▪${normal} "
+		PS1="${TITLEBAR:-}${bold_red?}┌─${reset_color?}${scm_prompt}[${cyan?}\u${normal?}][${cyan?}\w${normal?}]${is_vim_shell}\n${bold_red?}└─▪${normal?} "
 	else
-		PS1="${TITLEBAR}┌─$(scm_prompt)[${cyan}\u${normal}][${cyan}\w${normal}]$(is_vim_shell)\n└─▪ "
+		PS1="${TITLEBAR:-}┌─${scm_prompt}[${cyan?}\u${normal?}][${cyan?}\w${normal?}]${is_vim_shell}\n└─▪ "
 	fi
 	detect_venv
-	PS1+="${python_venv}${dir_color}"
+	PS1+="${python_venv?}${dir_color?}"
 }
 
 PS2="└─▪ "