diff --git a/docker-compose.yml b/docker-compose.yml
index a6adf34..a53a2c1 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -11,6 +11,7 @@ services:
       NEXT_TELEMETRY_DISABLED: "1"
       NEXT_PUBLIC_SITE_URL: ${NEXT_PUBLIC_SITE_URL:-https://mohfarawati.de}
       NEXT_PUBLIC_ADMIN_URL: ${NEXT_PUBLIC_ADMIN_URL:-https://root.mohfarawati.de}
+      SITE_RUNTIME_ORIGIN: ${SITE_RUNTIME_ORIGIN:-http://127.0.0.1:3000}
       DATABASE_URL: postgresql://postgres:postgres@db:5432/moh_sass?schema=public
       ADMIN_PASSWORD: ${ADMIN_PASSWORD:-change-me}
       ADMIN_AUTH_SECRET: ${ADMIN_AUTH_SECRET:-change-me-long-secret}
diff --git a/middleware.ts b/middleware.ts
index 9af1e6b..444b0ee 100644
--- a/middleware.ts
+++ b/middleware.ts
@@ -28,6 +28,20 @@ type SiteRuntimeState = {
   maintenanceEnabled: boolean;
 };
 
+function getSiteRuntimeStateOrigin(request: NextRequest): string {
+  const configuredOrigin = process.env.SITE_RUNTIME_ORIGIN?.trim();
+
+  if (configuredOrigin) {
+    return configuredOrigin;
+  }
+
+  if (process.env.NODE_ENV === "production") {
+    return "http://127.0.0.1:3000";
+  }
+
+  return request.nextUrl.origin;
+}
+
 function getPathLocale(pathname: string, fallbackLocale: (typeof appLocales)[number]) {
   const locale = pathname.split("/")[1];
 
@@ -40,8 +54,8 @@ function isComingSoonPath(pathname: string) {
 
 async function getSiteRuntimeState(request: NextRequest): Promise<SiteRuntimeState> {
   try {
-    const runtimeStateUrl = new URL("/api/site/default-locale", request.url);
-    const response = await fetch(new URL("/api/site/default-locale", request.url), {
+    const runtimeStateUrl = new URL("/api/site/default-locale", getSiteRuntimeStateOrigin(request));
+    const response = await fetch(runtimeStateUrl, {
       headers: {
         "x-middleware-request": "1",
       },
@@ -74,8 +88,8 @@ async function getSiteRuntimeState(request: NextRequest): Promise<SiteRuntimeSta
       defaultLocale: isSupportedLocale(data.defaultLocale) ? data.defaultLocale : FALLBACK_LOCALE,
       maintenanceEnabled: data.maintenanceEnabled === true,
     };
-  } catch {
-    console.error("middleware:getSiteRuntimeState:failed");
+  } catch (error) {
+    console.error("middleware:getSiteRuntimeState:failed", error);
     return {
       defaultLocale: FALLBACK_LOCALE,
       maintenanceEnabled: false,
diff --git a/tests/middleware.test.ts b/tests/middleware.test.ts
index 1d06c42..3d872e8 100644
--- a/tests/middleware.test.ts
+++ b/tests/middleware.test.ts
@@ -39,6 +39,8 @@ function createMockRequest(url: string) {
 describe("middleware locale runtime config", () => {
   beforeEach(() => {
     vi.resetModules();
+    process.env.NODE_ENV = "production";
+    delete process.env.SITE_RUNTIME_ORIGIN;
     createMiddlewareMock.mockReset();
     intlHandlerMock.mockReset();
     intlHandlerMock.mockReturnValue(NextResponse.next());
@@ -66,6 +68,10 @@ describe("middleware locale runtime config", () => {
 
     await middleware(request as never);
 
+    expect(fetch).toHaveBeenCalledWith(
+      new URL("http://127.0.0.1:3000/api/site/default-locale"),
+      expect.any(Object),
+    );
     expect(createMiddlewareMock).toHaveBeenCalledTimes(1);
     expect(createMiddlewareMock).toHaveBeenCalledWith(
       expect.objectContaining({
@@ -115,4 +121,29 @@ describe("middleware locale runtime config", () => {
     expect(response.headers.get("location")).toBe("https://example.com/coming-soon");
     expect(intlHandlerMock).not.toHaveBeenCalled();
   });
+
+  it("prefers the configured internal runtime origin when provided", async () => {
+    process.env.SITE_RUNTIME_ORIGIN = "http://app:3000";
+
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(async () => ({
+        ok: true,
+        json: async () => ({
+          defaultLocale: "en",
+          maintenanceEnabled: false,
+        }),
+      })),
+    );
+
+    const { default: middleware } = await import("../middleware");
+    const request = createMockRequest("https://example.com/");
+
+    await middleware(request as never);
+
+    expect(fetch).toHaveBeenCalledWith(
+      new URL("http://app:3000/api/site/default-locale"),
+      expect.any(Object),
+    );
+  });
 });