diff --git a/src/renderer/python/pyodideAssetUrl.ts b/src/renderer/python/pyodideAssetUrl.ts
index 5b243e5..f6de9a6 100644
--- a/src/renderer/python/pyodideAssetUrl.ts
+++ b/src/renderer/python/pyodideAssetUrl.ts
@@ -1,3 +1,9 @@
-export function resolvePyodideIndexURL(workerModuleUrl: string): string {
+export function resolvePyodideIndexURL(workerModuleUrl: string): string | undefined {
+  const parsed = new URL(workerModuleUrl);
+
+  if (parsed.protocol !== 'file:') {
+    return undefined;
+  }
+
   return new URL('../../../node_modules/pyodide/', workerModuleUrl).toString();
 }
diff --git a/src/renderer/python/pythonRuntime.worker.ts b/src/renderer/python/pythonRuntime.worker.ts
index 6ff43e6..d27bf54 100644
--- a/src/renderer/python/pythonRuntime.worker.ts
+++ b/src/renderer/python/pythonRuntime.worker.ts
@@ -183,8 +183,9 @@ json.dumps(__bds_entrypoints)
 
 async function bootstrapRuntime(): Promise<void> {
   try {
+    const indexURL = resolvePyodideIndexURL(import.meta.url);
     runtime = await loadPyodide({
-      indexURL: resolvePyodideIndexURL(import.meta.url),
+      ...(indexURL ? { indexURL } : {}),
       stdout: (chunk) => {
         if (!activeRequestId) {
           return;
diff --git a/tests/renderer/python/pyodideAssetUrl.test.ts b/tests/renderer/python/pyodideAssetUrl.test.ts
index 3fc99f1..d175dca 100644
--- a/tests/renderer/python/pyodideAssetUrl.test.ts
+++ b/tests/renderer/python/pyodideAssetUrl.test.ts
@@ -9,8 +9,13 @@ describe('resolvePyodideIndexURL', () => {
     );
   });
 
-  it('resolves to vite node_modules path for dev worker urls', () => {
+  it('returns undefined for dev worker urls to let pyodide use module-relative defaults', () => {
     const workerUrl = 'http://localhost:5173/src/renderer/python/pythonRuntime.worker.ts';
-    expect(resolvePyodideIndexURL(workerUrl)).toBe('http://localhost:5173/node_modules/pyodide/');
+    expect(resolvePyodideIndexURL(workerUrl)).toBeUndefined();
+  });
+
+  it('returns undefined for vite worker_file urls with query parameters', () => {
+    const workerUrl = 'http://localhost:5173/python/pythonRuntime.worker.ts?worker_file&type=module';
+    expect(resolvePyodideIndexURL(workerUrl)).toBeUndefined();
   });
 });