diff --git a/doc/libpkgconf-path.rst b/doc/libpkgconf-path.rst
index a79be05..658f890 100644
--- a/doc/libpkgconf-path.rst
+++ b/doc/libpkgconf-path.rst
@@ -34,7 +34,7 @@ variables.
    :return: number of path nodes added to the path list
    :rtype: size_t
 
-.. c:function:: bool pkgconf_path_match_list(const char *path, pkgconf_list_t *dirlist)
+.. c:function:: bool pkgconf_path_match_list(const char *path, const pkgconf_list_t *dirlist)
 
    Checks whether a path has a matching prefix in a path list.
 
diff --git a/libpkgconf/libpkgconf.h b/libpkgconf/libpkgconf.h
index 073803f..1b7096b 100644
--- a/libpkgconf/libpkgconf.h
+++ b/libpkgconf/libpkgconf.h
@@ -136,10 +136,8 @@ struct pkgconf_client_ {
 	pkgconf_list_t dir_list;
 	pkgconf_list_t pkg_cache;
 
-#ifdef XXX_NOTYET
 	pkgconf_list_t filter_libdirs;
 	pkgconf_list_t filter_includedirs;
-#endif
 
 	pkgconf_list_t global_vars;
 
@@ -274,7 +272,7 @@ void pkgconf_audit_log_dependency(pkgconf_client_t *client, const pkgconf_pkg_t
 void pkgconf_path_add(const char *text, pkgconf_list_t *dirlist);
 size_t pkgconf_path_split(const char *text, pkgconf_list_t *dirlist);
 size_t pkgconf_path_build_from_environ(const char *environ, const char *fallback, pkgconf_list_t *dirlist);
-bool pkgconf_path_match_list(const char *path, pkgconf_list_t *dirlist);
+bool pkgconf_path_match_list(const char *path, const pkgconf_list_t *dirlist);
 void pkgconf_path_free(pkgconf_list_t *dirlist);
 
 #endif
diff --git a/libpkgconf/path.c b/libpkgconf/path.c
index b83a039..320e20c 100644
--- a/libpkgconf/path.c
+++ b/libpkgconf/path.c
@@ -114,7 +114,7 @@ pkgconf_path_build_from_environ(const char *environ, const char *fallback, pkgco
 /*
  * !doc
  *
- * .. c:function:: bool pkgconf_path_match_list(const char *path, pkgconf_list_t *dirlist)
+ * .. c:function:: bool pkgconf_path_match_list(const char *path, const pkgconf_list_t *dirlist)
  *
  *    Checks whether a path has a matching prefix in a path list.
  *
@@ -124,7 +124,7 @@ pkgconf_path_build_from_environ(const char *environ, const char *fallback, pkgco
  *    :rtype: bool
  */
 bool
-pkgconf_path_match_list(const char *path, pkgconf_list_t *dirlist)
+pkgconf_path_match_list(const char *path, const pkgconf_list_t *dirlist)
 {
 	pkgconf_node_t *n = NULL;