diff --git a/cache.h b/cache.h
index ba04ff8..2a0fb3e 100644
--- a/cache.h
+++ b/cache.h
@@ -1288,6 +1288,13 @@ int looks_like_command_line_option(const char *str);
 
 /**
  * Return a newly allocated string with the evaluation of
+ * "$XDG_CONFIG_HOME/$subdir/$filename" if $XDG_CONFIG_HOME is non-empty, otherwise
+ * "$HOME/.config/$subdir/$filename". Return NULL upon error.
+ */
+char *xdg_config_home_for(const char *subdir, const char *filename);
+
+/**
+ * Return a newly allocated string with the evaluation of
  * "$XDG_CONFIG_HOME/git/$filename" if $XDG_CONFIG_HOME is non-empty, otherwise
  * "$HOME/.config/git/$filename". Return NULL upon error.
  */