diff --git a/clean_files.txt b/clean_files.txt
index 8f9c173a29..5889b7d6d3 100644
--- a/clean_files.txt
+++ b/clean_files.txt
@@ -165,6 +165,7 @@ themes/modern
 themes/norbu
 themes/pete
 themes/powerline
+themes/powerline-plain
 themes/pure
 themes/purity
 
diff --git a/themes/powerline-plain/powerline-plain.theme.bash b/themes/powerline-plain/powerline-plain.theme.bash
index 1f2900efce..7c1a61606e 100644
--- a/themes/powerline-plain/powerline-plain.theme.bash
+++ b/themes/powerline-plain/powerline-plain.theme.bash
@@ -3,17 +3,19 @@
 # shellcheck source-path=SCRIPTDIR/../powerline
 source "${BASH_IT?}/themes/powerline/powerline.base.bash"
 
+PROMPT_CHAR="${POWERLINE_PROMPT_CHAR:=""}"
+
+: "${POWERLINE_COMPACT:=0}"
+: "${POWERLINE_COMPACT_BEFORE_SEPARATOR:=${POWERLINE_COMPACT}}"
+: "${POWERLINE_COMPACT_AFTER_SEPARATOR:=${POWERLINE_COMPACT}}"
+: "${POWERLINE_COMPACT_BEFORE_FIRST_SEGMENT:=${POWERLINE_COMPACT}}"
+: "${POWERLINE_COMPACT_AFTER_LAST_SEGMENT:=${POWERLINE_COMPACT}}"
+: "${POWERLINE_COMPACT_PROMPT:=${POWERLINE_COMPACT}}"
+
 USER_INFO_SSH_CHAR=${POWERLINE_USER_INFO_SSH_CHAR:="⌁ "}
 USER_INFO_THEME_PROMPT_COLOR=${POWERLINE_USER_INFO_COLOR:=32}
 USER_INFO_THEME_PROMPT_COLOR_SUDO=${POWERLINE_USER_INFO_COLOR_SUDO:=202}
 
-POWERLINE_COMPACT=${POWERLINE_COMPACT:=0}
-POWERLINE_COMPACT_BEFORE_SEPARATOR=${POWERLINE_COMPACT_BEFORE_SEPARATOR:=${POWERLINE_COMPACT}}
-POWERLINE_COMPACT_AFTER_SEPARATOR=${POWERLINE_COMPACT_AFTER_SEPARATOR:=${POWERLINE_COMPACT}}
-POWERLINE_COMPACT_BEFOR_FIRST_SEGMENT=${POWERLINE_COMPACT_BEFORE_FIRST_SEGMENT:=${POWERLINE_COMPACT}}
-POWERLINE_COMPACT_AFTER_LAST_SEGMENT=${POWERLINE_COMPACT_AFTER_LAST_SEGMENT:=${POWERLINE_COMPACT}}
-POWERLINE_COMPACT_PROMPT=${POWERLINE_COMPACT_PROMPT:=${POWERLINE_COMPACT}}
-
 PYTHON_VENV_CHAR=${POWERLINE_PYTHON_VENV_CHAR:="ⓔ "}
 CONDA_PYTHON_VENV_CHAR=${POWERLINE_CONDA_PYTHON_VENV_CHAR:="ⓔ "}
 PYTHON_VENV_THEME_PROMPT_COLOR=${POWERLINE_PYTHON_VENV_COLOR:=35}
@@ -59,12 +61,12 @@ LAST_STATUS_THEME_PROMPT_COLOR=${POWERLINE_LAST_STATUS_COLOR:=52}
 
 CLOCK_THEME_PROMPT_COLOR=${POWERLINE_CLOCK_COLOR:=240}
 
-BATTERY_AC_CHAR=${BATTERY_AC_CHAR:="+ "}
+: "${BATTERY_AC_CHAR:="+ "}"
 BATTERY_STATUS_THEME_PROMPT_GOOD_COLOR=${POWERLINE_BATTERY_GOOD_COLOR:=70}
 BATTERY_STATUS_THEME_PROMPT_LOW_COLOR=${POWERLINE_BATTERY_LOW_COLOR:=208}
 BATTERY_STATUS_THEME_PROMPT_CRITICAL_COLOR=${POWERLINE_BATTERY_CRITICAL_COLOR:=160}
 
-THEME_CLOCK_FORMAT=${THEME_CLOCK_FORMAT:="%H:%M:%S"}
+: "${THEME_CLOCK_FORMAT:="%H:%M:%S"}"
 
 IN_VIM_THEME_PROMPT_COLOR=${POWERLINE_IN_VIM_COLOR:=245}
 IN_VIM_THEME_PROMPT_TEXT=${POWERLINE_IN_VIM_TEXT:="vim"}
@@ -89,6 +91,6 @@ COMMAND_NUMBER_THEME_PROMPT_CHAR=${POWERLINE_COMMAND_NUMBER_CHAR:="#"}
 GCLOUD_THEME_PROMPT_COLOR=${POWERLINE_GCLOUD_COLOR:=161}
 GCLOUD_CHAR=${POWERLINE_GCLOUD_CHAR:="❲G❳ "}
 
-POWERLINE_PROMPT=${POWERLINE_PROMPT:="user_info scm python_venv ruby node cwd"}
+: "${POWERLINE_PROMPT:="user_info scm python_venv ruby node cwd"}"
 
 safe_append_prompt_command __powerline_prompt_command