diff --git a/runtime/pack/dist/opt/helptoc/autoload/helptoc.vim b/runtime/pack/dist/opt/helptoc/autoload/helptoc.vim
index 087da79..c0d86a4 100644
--- a/runtime/pack/dist/opt/helptoc/autoload/helptoc.vim
+++ b/runtime/pack/dist/opt/helptoc/autoload/helptoc.vim
@@ -2,9 +2,20 @@
 
 # Config {{{1
 
-const SHELL_PROMPT: string = g:
-    ->get('helptoc', {})
-    ->get('shell_prompt', '^\w\+@\w\+:\f\+\$\s')
+var SHELL_PROMPT: string = ''
+
+def UpdateUserSettings() #{{{2
+    var new_prompt: string = g:
+        ->get('helptoc', {})
+        ->get('shell_prompt', '^\w\+@\w\+:\f\+\$\s')
+    if new_prompt != SHELL_PROMPT
+        SHELL_PROMPT = new_prompt
+        # invalidate cache: user config has changed
+        unlet! b:toc
+    endif
+enddef
+
+UpdateUserSettings()
 
 # Init {{{1
 
@@ -141,6 +152,8 @@
         return
     endif
 
+    UpdateUserSettings()
+
     # invalidate the cache if the buffer's contents has changed
     if exists('b:toc') && &filetype != 'man'
         if b:toc.changedtick != b:changedtick