diff --git a/packages/core/src/utils/overpass/client.test.ts b/packages/core/src/utils/overpass/client.test.ts
index 5d27e0e40..227f90923 100644
--- a/packages/core/src/utils/overpass/client.test.ts
+++ b/packages/core/src/utils/overpass/client.test.ts
@@ -20,6 +20,21 @@ afterEach(() => {
 });
 
 describe("overpassQuery", () => {
+  it("sends OVERPASS_URL credentials as Basic auth, which fetch refuses in the URL", async () => {
+    vi.stubEnv("OVERPASS_URL", "https://mapper:s3cret@overpass.example.org");
+    const fetchMock = vi.fn(
+      async (_url: string, _init?: RequestInit) =>
+        new Response(JSON.stringify({ elements: [] }), { status: 200 }),
+    );
+    vi.stubGlobal("fetch", fetchMock);
+
+    await expect(overpassQuery(QUERY)).resolves.toMatchObject({ elements: [] });
+    expect(fetchMock.mock.calls[0]?.[0]).toBe("https://overpass.example.org/api/interpreter");
+    expect(new Headers(fetchMock.mock.calls[0]?.[1]?.headers).get("Authorization")).toBe(
+      `Basic ${Buffer.from("mapper:s3cret").toString("base64")}`,
+    );
+  });
+
   it("reports a server that does not answer in time as unavailable, not as a 500", async () => {
     setOverpassUrl("http://overpass.test");
     vi.stubGlobal(
diff --git a/packages/core/src/utils/overpass/client.ts b/packages/core/src/utils/overpass/client.ts
index f1f2eda48..22b605497 100644
--- a/packages/core/src/utils/overpass/client.ts
+++ b/packages/core/src/utils/overpass/client.ts
@@ -1,6 +1,7 @@
 import { type Attribution, OPENSTREETMAP_ATTRIBUTION } from "@openmapx/mobility-core/attribution";
 import { snapshotContributors } from "@openmapx/mobility-core/contributors";
 import { type ResolvedPlatformEndpoint, resolvePlatformEndpoint } from "../platform-endpoints";
+import { urlCredentialsAsBasicAuth } from "../url-credentials";
 import { USER_AGENT } from "../userAgent";
 import type { OverpassResponse } from "./types";
 
@@ -127,13 +128,17 @@ function overpassErrorPageError(text: string): Error {
 const OVERPASS_REQUEST_TIMEOUT_MS = 35_000;
 
 async function fetchOverpass(url: string, query: string): Promise<OverpassResponse> {
-  const contributors = snapshotContributors(captureSupplier(url));
+  // An operator's `https://user:pass@host` goes as Basic auth: fetch refuses
+  // a URL carrying credentials and names the whole URL in its error.
+  const target = urlCredentialsAsBasicAuth(url);
+  const contributors = snapshotContributors(captureSupplier(target.url));
   try {
-    const res = await fetch(url, {
+    const res = await fetch(target.url, {
       method: "POST",
       headers: {
         "Content-Type": "application/x-www-form-urlencoded",
         "User-Agent": USER_AGENT,
+        ...(target.authorization ? { Authorization: target.authorization } : {}),
       },
       body: `data=${encodeURIComponent(query)}`,
       signal: AbortSignal.timeout(OVERPASS_REQUEST_TIMEOUT_MS),