diff --git a/packages/miniflare/src/index.ts b/packages/miniflare/src/index.ts
index 3d3125592100..f429e1f80e5a 100644
--- a/packages/miniflare/src/index.ts
+++ b/packages/miniflare/src/index.ts
@@ -421,6 +421,7 @@ export class Miniflare {
 		try {
 			const customService = request.headers.get(HEADER_CUSTOM_SERVICE);
 			if (customService !== null) {
+				request.headers.delete(HEADER_CUSTOM_SERVICE);
 				response = await this.#handleLoopbackCustomService(
 					request,
 					customService
diff --git a/packages/miniflare/test/index.spec.ts b/packages/miniflare/test/index.spec.ts
index 46224206fe49..f238bb32aa6e 100644
--- a/packages/miniflare/test/index.spec.ts
+++ b/packages/miniflare/test/index.spec.ts
@@ -60,6 +60,9 @@ test("Miniflare: web socket kitchen sink", async (t) => {
 			CUSTOM(request) {
 				// Testing dispatchFetch custom cf injection
 				t.deepEqual(request.cf, { country: "MF" });
+				// Testing `MF-Custom-Service` header removed:
+				// https://github.com/cloudflare/miniflare/issues/475
+				t.is(request.headers.get("MF-Custom-Service"), null);
 				// Testing WebSocket-upgrading fetch
 				return fetch(`http://localhost:${port}`, request);
 			},