diff --git a/clients/client-s3/test/unit/dotSegmentInUriLabel.spec.ts b/clients/client-s3/test/unit/dotSegmentInUriLabel.spec.ts
new file mode 100644
index 000000000000..e34075bc35ba
--- /dev/null
+++ b/clients/client-s3/test/unit/dotSegmentInUriLabel.spec.ts
@@ -0,0 +1,69 @@
+/// <reference types="mocha" />
+import { HttpHandler, HttpRequest, HttpResponse } from "@smithy/protocol-http";
+import { HttpHandlerOptions } from "@smithy/types";
+import { S3 } from "../../src/S3";
+import chai from "chai";
+import chaiAsPromised from "chai-as-promised";
+
+chai.use(chaiAsPromised);
+const { expect } = chai;
+
+/**
+ * Throws an expected exception that contains the serialized request.
+ */
+class ExpectedRequestSerializationError extends Error {
+  constructor(readonly request: HttpRequest) {
+    super();
+  }
+}
+
+class RequestSerializationTestHandler implements HttpHandler {
+  async handle(request: HttpRequest, options?: HttpHandlerOptions): Promise<{ response: HttpResponse }> {
+    throw new ExpectedRequestSerializationError(request);
+  }
+  updateHttpClientConfig(key: never, value: never): void {}
+  httpHandlerConfigs() {
+    return {};
+  }
+}
+
+describe("Dot Segment in URI Label", () => {
+  const client = new S3({
+    credentials: { accessKeyId: "mockAccessKeyId", secretAccessKey: "mockSecretAccessKey" },
+    requestHandler: new RequestSerializationTestHandler(),
+  });
+
+  it("S3PreservesLeadingDotSegmentInUriLabel", async () => {
+    try {
+      await client.getObject({
+        Bucket: "mybucket",
+        Key: "../key.txt",
+      });
+      fail("Expected an EXPECTED_REQUEST_SERIALIZATION_ERROR to be thrown");
+    } catch (err) {
+      if (!(err instanceof ExpectedRequestSerializationError)) {
+        fail(err);
+      }
+      const r = err.request;
+      expect(r.method).to.eql("GET");
+      expect(r.path).to.eql("/../key.txt");
+    }
+  });
+
+  it("S3PreservesEmbeddedDotSegmentInUriLabel", async () => {
+    try {
+      await client.getObject({
+        Bucket: "mybucket",
+        Key: "foo/../key.txt",
+      });
+      fail("Expected an EXPECTED_REQUEST_SERIALIZATION_ERROR to be thrown");
+    } catch (err) {
+      if (!(err instanceof ExpectedRequestSerializationError)) {
+        fail(err);
+      }
+      const r = err.request;
+      expect(r.method).to.eql("GET");
+      expect(r.path).to.eql("/foo/../key.txt");
+    }
+  });
+});