diff --git a/types/plugin.d.ts b/types/plugin.d.ts
index 2ad5cc8..13929fa 100644
--- a/types/plugin.d.ts
+++ b/types/plugin.d.ts
@@ -1,13 +1,17 @@
 import type { RouteLocationRaw, RouteRecordRaw, RouteRecordName } from 'vue-router';
 import type { Component } from '@vue/runtime-core';
 
+/* This is some sort of PEP440 subset */
 type Join<T extends unknown[], D extends string> =
     T extends [] ? '' :
     T extends [string | number | boolean | bigint] ? `${T[0]}` :
     T extends [string | number | boolean | bigint, ...infer U] ? `${T[0]}${D}${Join<U, D>}` :
     string;
-type BVersion = Join<[number, number], '.'> | Join<[number, number, number], '.'>
-type Version = BVersion | Join<[BVersion, string], '-'>
+type BaseVersion = Join<[number, number], '.'> | Join<[number, number, number], '.'>
+type PreRelease = Join<[["a"|"b"|"rc"], number], ".">
+type PRVersion = BaseVersion | `${BaseVersion}${PreRelease}`
+/** A PEP440 subset used to describe backend module versions */
+export type PEP440Version = PRVersion | `${PRVersion}.dev${number}`
 
 export namespace FG_Plugin {
   /**
@@ -22,10 +26,8 @@ export namespace FG_Plugin {
     version: string;
     /** Widgets provided by this plugin */
     widgets: Widget[];
-    /** Other frontend modules needed for this plugin to work correctly */
-    requiredModules: [string, Version?][];
     /** Backend modules needed for this plugin to work correctly */
-    requiredBackendModules: [string, Version?][];
+    requiredModules: [string, PEP440Version?][];
     /** Menu entries for authenticated users */
     innerRoutes?: MenuRoute[];
     /** Public menu entries (without authentification) */