diff --git a/docs/contributing.md b/docs/contributing.md
index a09ede7d..0692fd8b 100644
--- a/docs/contributing.md
+++ b/docs/contributing.md
@@ -125,6 +125,7 @@ For web development on the controller there are also the following flags:
 `--dev` - Serve the `web_ui` package from source through Vite's development server with hot module replacement.
 
 `--dev-plugin [name]` - Serve the web module for the given plugin from source the same way.
+This also serves the `web_ui` package from source, as the plugin has to share its modules with it.
 
 These options can be combined and multiple plugins can be actived for dev mode.
 Keep in mind if you're working on external plugins the `--dev-plugin` option is likely to only work if the plugin is placed inside the `external_plugins` directory and its dependencies are installed with pnpm as part of the clusterio repository workspace.
diff --git a/packages/controller/src/Controller.ts b/packages/controller/src/Controller.ts
index 1d006df9..6bf88250 100644
--- a/packages/controller/src/Controller.ts
+++ b/packages/controller/src/Controller.ts
@@ -426,7 +426,7 @@ export default class Controller {
 			this.app.use(this.devServer.middlewares);
 		}
 
-		if (!args.dev) {
+		if (!this.devServer) {
 			let manifestPath = path.join(import.meta.dirname, "..", "..", "web", "manifest.json");
 
 			let manifest = await Controller.loadJsonObject(manifestPath);
@@ -534,14 +534,14 @@ export default class Controller {
 			},
 			plugins: [webUiVite.clusterioDevPlugins(pluginDirs)],
 		});
-		if (args.dev) {
-			this.app.locals.webBundle = {
-				main: this.devServer.config.plugins.find(p => p.name === "clusterio:app")!.api.entry,
-				imports: Object.fromEntries(webUiVite.sharedModules.map(
-					name => [name, webUiVite.devSharedUrl(name)]
-				)),
-			};
-		}
+		// Plugins served from source import the shared modules from the development server, the web
+		// interface has to use the same copies, so it is served from source as well with --dev-plugin.
+		this.app.locals.webBundle = {
+			main: this.devServer.config.plugins.find(p => p.name === "clusterio:app")!.api.entry,
+			imports: Object.fromEntries(webUiVite.sharedModules.map(
+				name => [name, webUiVite.devSharedUrl(name)]
+			)),
+		};
 		this.app.locals.devServer = this.devServer;
 	}