diff --git a/apps/backend/src/app/api/latest/projects/[project_id]/.well-known/jwks.json/route.ts b/apps/backend/src/app/api/latest/projects/[project_id]/.well-known/jwks.json/route.ts
index ce3060f84..c2880e41a 100644
--- a/apps/backend/src/app/api/latest/projects/[project_id]/.well-known/jwks.json/route.ts
+++ b/apps/backend/src/app/api/latest/projects/[project_id]/.well-known/jwks.json/route.ts
@@ -1,4 +1,4 @@
-import { yupArray, yupNumber, yupObject, yupString } from "@stackframe/stack-shared/dist/schema-fields";
+import { yupArray, yupNumber, yupObject, yupString, yupTuple } from "@stackframe/stack-shared/dist/schema-fields";
 import { StatusError } from "@stackframe/stack-shared/dist/utils/errors";
 import { deindent } from "@stackframe/stack-shared/dist/utils/strings";
 import { getProject } from "../../../../../../../lib/projects";
@@ -27,7 +27,9 @@ export const GET = createSmartRouteHandler({
     body: yupObject({
       keys: yupArray().defined(),
     }).defined(),
-
+    headers: yupObject({
+      "Cache-Control": yupTuple([yupString().defined()]).defined(),
+    }).defined(),
   }),
   async handler({ params, query }) {
     const project = await getProject(params.project_id);
@@ -42,7 +44,7 @@ export const GET = createSmartRouteHandler({
       body: await getPublicProjectJwkSet(params.project_id, query.include_anonymous === "true"),
       headers: {
         // Cache for 1 hour
-        "Cache-Control": "public, max-age=3600",
+        "Cache-Control": ["public, max-age=3600"] as const,
       },
     };
   },
diff --git a/apps/backend/src/route-handlers/smart-response.tsx b/apps/backend/src/route-handlers/smart-response.tsx
index e64206a00..e1116fb6b 100644
--- a/apps/backend/src/route-handlers/smart-response.tsx
+++ b/apps/backend/src/route-handlers/smart-response.tsx
@@ -122,16 +122,16 @@ export async function createResponse<T extends SmartResponse>(req: NextRequest |
       headers.set("x-stack-actual-status", [obj.statusCode.toString()]);
     }
 
+    // set all headers from the smart response (considering case insensitivity)
+    for (const [key, values] of Object.entries(obj.headers ?? {})) {
+        headers.set(key.toLowerCase(), values);
+    }
+
     return new Response(
       arrayBufferBody,
       {
         status,
-        headers: [
-          ...Object.entries({
-            ...Object.fromEntries(headers),
-            ...obj.headers ?? {}
-          }).flatMap(([key, values]) => values.map(v => [key.toLowerCase(), v!] as [string, string])),
-        ],
+        headers: [...headers].flatMap(([key, values]) => values.map(v => [key, v] satisfies [string, string])),
       },
     );
   });
diff --git a/apps/e2e/tests/backend/endpoints/api/v1/projects.test.ts b/apps/e2e/tests/backend/endpoints/api/v1/projects.test.ts
index 57ba1dc85..a182b2652 100644
--- a/apps/e2e/tests/backend/endpoints/api/v1/projects.test.ts
+++ b/apps/e2e/tests/backend/endpoints/api/v1/projects.test.ts
@@ -1477,6 +1477,7 @@ it("has a correctly formatted JWKS endpoint", async ({ expect }) => {
   const response = await niceBackendFetch("/api/v1/projects/internal/.well-known/jwks.json");
   expect(response.status).toBe(200);
   expect(response.headers.get("content-type")).includes("application/json");
+  expect(response.headers.get("cache-control")).toBe("public, max-age=3600");
   expect(response.body).toEqual({
     keys: [
       {