diff --git a/src/Previewer/previewer.vala b/src/Previewer/previewer.vala
index b5ae8a9a2..6e54adf3c 100644
--- a/src/Previewer/previewer.vala
+++ b/src/Previewer/previewer.vala
@@ -122,68 +122,42 @@ namespace Workbench {
       Gtk.StyleContext.add_provider_for_display (Gdk.Display.get_default (), this.css , Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION);
     }
 
-    // filename to loadable module or empty string ("") to just run it again
-    // also builder_symbol can be empty. Then the builder object is not handed over to the module
-    public void run (string filename, string run_symbol, string builder_symbol, string window_symbol, string uri) {
-      void* function;
-
-      if (filename == "") {
-        if (this.module == null) {
-          stderr.printf ("No Module specified yet.\n");
-          return;
-        }
-      } else {
-        if (!Module.supported ()) {
-          stderr.printf ("This system does not support loadable modules.\n");
-          return;
-        }
+    public void run (string filename, string uri) {
+      if (this.module != null) {
+        this.module.close ();
+      }
 
-        if (this.module != null)
-          this.module.close ();
-        this.module = Module.open (filename, ModuleFlags.LAZY);
-        if (this.module == null) {
-          stderr.printf ("Module loading failed.\n");
-          return;
-        }
+      this.module = Module.open (filename, ModuleFlags.LAZY);
+      if (this.module == null) {
+        stderr.printf ("Module loading failed.\n");
+        return;
       }
 
+      void* function;
+
       this.module.symbol ("set_base_uri", out function);
       var set_base_uri = (BaseUriFunction) function;
       set_base_uri (uri);
 
-      if (builder_symbol != "") {
-        if (this.builder == null) {
-          stderr.printf ("No UI definition loaded yet.\n");
-          return;
-        }
-
-        this.module.symbol (builder_symbol, out function);
-        if (function == null) {
-          stderr.printf (@"Module does not contain symbol '$builder_symbol'.\n");
-          return;
-        }
-
-        var set_builder = (BuilderFunction) function;
+      this.module.symbol ("set_builder", out function);
+      var set_builder = (BuilderFunction) function;
+      if (this.builder != null) {
         set_builder (this.builder);
+      }
 
-        this.module.symbol (window_symbol, out function);
-        if (function == null) {
-          stderr.printf (@"Module does not contain symbol '$window_symbol'.\n");
-          return;
-        }
-
-        var set_window = (WindowFunction) function;
+      this.module.symbol ("set_window", out function);
+      var set_window = (WindowFunction) function;
+      if (this.window != null) {
         set_window (this.window);
       }
 
-      this.module.symbol (run_symbol, out function);
+      this.module.symbol ("main", out function);
       if (function == null) {
-        stderr.printf (@"Function '$run_symbol' not found.\n");
+        stderr.printf (@"Function 'main' not found.\n");
         return;
       }
-
-      var run = (RunFunction) function;
-      run ();
+      var main_function = (MainFunction) function;
+      main_function ();
     }
 
     public void close_window () {
@@ -211,7 +185,7 @@ namespace Workbench {
     public signal void css_parser_error (string message, int start_line, int start_char, int end_line, int end_char);
 
     [CCode (has_target=false)]
-    private delegate void RunFunction ();
+    private delegate void MainFunction ();
 
     [CCode (has_target=false)]
     private delegate void BuilderFunction (Gtk.Builder builder);
@@ -231,6 +205,11 @@ namespace Workbench {
   }
 
   void main (string[] args) {
+    if (!Module.supported ()) {
+      stderr.printf ("This system does not support loadable modules.\n");
+      Process.exit (1);
+    }
+
     var loop = new MainLoop();
 
     Adw.init();
diff --git a/src/Previewer/previewer.xml b/src/Previewer/previewer.xml
index 40488d955..a5cdfedd1 100644
--- a/src/Previewer/previewer.xml
+++ b/src/Previewer/previewer.xml
@@ -10,9 +10,6 @@
     </method>
     <method name="Run">
       <arg type="s" name="filename" direction="in"/>
-      <arg type="s" name="run_symbol" direction="in"/>
-      <arg type="s" name="builder_symbol" direction="in"/>
-      <arg type="s" name="window_symbol" direction="in"/>
       <arg type="s" name="uri" direction="in"/>
     </method>
     <method name="CloseWindow">
diff --git a/src/langs/vala/Compiler.js b/src/langs/vala/Compiler.js
index dbe723cc8..9e7e4a4c9 100644
--- a/src/langs/vala/Compiler.js
+++ b/src/langs/vala/Compiler.js
@@ -1,5 +1,4 @@
 import Gio from "gi://Gio";
-import GLib from "gi://GLib";
 import dbus_previewer from "../../Previewer/DBusPreviewer.js";
 import { decode } from "../../util.js";
 
@@ -21,8 +20,6 @@ export default function Compiler({ session }) {
       return;
     }
 
-    await module_file.delete_async(GLib.PRIORITY_DEFAULT, null).catch(() => {});
-
     const valac_launcher = new Gio.SubprocessLauncher();
     valac_launcher.set_cwd(file.get_path());
     const valac = valac_launcher.spawnv([
@@ -52,13 +49,7 @@ export default function Compiler({ session }) {
   async function run() {
     try {
       const proxy = await dbus_previewer.getProxy();
-      await proxy.RunAsync(
-        module_file.get_path(),
-        "main",
-        "set_builder",
-        "set_window",
-        session.file.get_uri(),
-      );
+      await proxy.RunAsync(module_file.get_path(), session.file.get_uri());
     } catch (err) {
       logError(err);
       return false;
diff --git a/src/langs/vala/workbench.vala b/src/langs/vala/workbench.vala
index 51d88af97..dfb3a301b 100644
--- a/src/langs/vala/workbench.vala
+++ b/src/langs/vala/workbench.vala
@@ -7,12 +7,12 @@ namespace workbench {
     }
 }
 
-public void set_builder (Gtk.Builder b) {
-    workbench.builder = b;
+public void set_builder (Gtk.Builder builder) {
+    workbench.builder = builder;
 }
 
-public void set_window (Gtk.Window w) {
-    workbench.window = w;
+public void set_window (Gtk.Window window) {
+    workbench.window = window;
 }
 
 public void set_base_uri (string uri) {