diff --git a/baselines/dom.generated.d.ts b/baselines/dom.generated.d.ts
index c4a1e58bd..776295c71 100644
--- a/baselines/dom.generated.d.ts
+++ b/baselines/dom.generated.d.ts
@@ -21839,6 +21839,7 @@ interface SubtleCrypto {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/SubtleCrypto/exportKey) */
     exportKey(format: "jwk", key: CryptoKey): Promise<JsonWebKey>;
     exportKey(format: Exclude<KeyFormat, "jwk">, key: CryptoKey): Promise<ArrayBuffer>;
+    exportKey(format: KeyFormat, key: CryptoKey): Promise<ArrayBuffer | JsonWebKey>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/SubtleCrypto/generateKey) */
     generateKey(algorithm: RsaHashedKeyGenParams | EcKeyGenParams, extractable: boolean, keyUsages: ReadonlyArray<KeyUsage>): Promise<CryptoKeyPair>;
     generateKey(algorithm: AesKeyGenParams | HmacKeyGenParams | Pbkdf2Params, extractable: boolean, keyUsages: ReadonlyArray<KeyUsage>): Promise<CryptoKey>;
diff --git a/baselines/serviceworker.generated.d.ts b/baselines/serviceworker.generated.d.ts
index 7b3b420c0..acb3fc37a 100644
--- a/baselines/serviceworker.generated.d.ts
+++ b/baselines/serviceworker.generated.d.ts
@@ -5016,6 +5016,7 @@ interface SubtleCrypto {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/SubtleCrypto/exportKey) */
     exportKey(format: "jwk", key: CryptoKey): Promise<JsonWebKey>;
     exportKey(format: Exclude<KeyFormat, "jwk">, key: CryptoKey): Promise<ArrayBuffer>;
+    exportKey(format: KeyFormat, key: CryptoKey): Promise<ArrayBuffer | JsonWebKey>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/SubtleCrypto/generateKey) */
     generateKey(algorithm: RsaHashedKeyGenParams | EcKeyGenParams, extractable: boolean, keyUsages: ReadonlyArray<KeyUsage>): Promise<CryptoKeyPair>;
     generateKey(algorithm: AesKeyGenParams | HmacKeyGenParams | Pbkdf2Params, extractable: boolean, keyUsages: ReadonlyArray<KeyUsage>): Promise<CryptoKey>;
diff --git a/baselines/sharedworker.generated.d.ts b/baselines/sharedworker.generated.d.ts
index 234617a85..e28f1c794 100644
--- a/baselines/sharedworker.generated.d.ts
+++ b/baselines/sharedworker.generated.d.ts
@@ -4827,6 +4827,7 @@ interface SubtleCrypto {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/SubtleCrypto/exportKey) */
     exportKey(format: "jwk", key: CryptoKey): Promise<JsonWebKey>;
     exportKey(format: Exclude<KeyFormat, "jwk">, key: CryptoKey): Promise<ArrayBuffer>;
+    exportKey(format: KeyFormat, key: CryptoKey): Promise<ArrayBuffer | JsonWebKey>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/SubtleCrypto/generateKey) */
     generateKey(algorithm: RsaHashedKeyGenParams | EcKeyGenParams, extractable: boolean, keyUsages: ReadonlyArray<KeyUsage>): Promise<CryptoKeyPair>;
     generateKey(algorithm: AesKeyGenParams | HmacKeyGenParams | Pbkdf2Params, extractable: boolean, keyUsages: ReadonlyArray<KeyUsage>): Promise<CryptoKey>;
diff --git a/baselines/webworker.generated.d.ts b/baselines/webworker.generated.d.ts
index e2b747f88..78abc74f6 100644
--- a/baselines/webworker.generated.d.ts
+++ b/baselines/webworker.generated.d.ts
@@ -5322,6 +5322,7 @@ interface SubtleCrypto {
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/SubtleCrypto/exportKey) */
     exportKey(format: "jwk", key: CryptoKey): Promise<JsonWebKey>;
     exportKey(format: Exclude<KeyFormat, "jwk">, key: CryptoKey): Promise<ArrayBuffer>;
+    exportKey(format: KeyFormat, key: CryptoKey): Promise<ArrayBuffer | JsonWebKey>;
     /** [MDN Reference](https://developer.mozilla.org/docs/Web/API/SubtleCrypto/generateKey) */
     generateKey(algorithm: RsaHashedKeyGenParams | EcKeyGenParams, extractable: boolean, keyUsages: ReadonlyArray<KeyUsage>): Promise<CryptoKeyPair>;
     generateKey(algorithm: AesKeyGenParams | HmacKeyGenParams | Pbkdf2Params, extractable: boolean, keyUsages: ReadonlyArray<KeyUsage>): Promise<CryptoKey>;
diff --git a/inputfiles/overridingTypes.jsonc b/inputfiles/overridingTypes.jsonc
index 750dec6cb..1525bfd1c 100644
--- a/inputfiles/overridingTypes.jsonc
+++ b/inputfiles/overridingTypes.jsonc
@@ -1572,17 +1572,18 @@
                         },
                         "exportKey": {
                             "additionalSignatures": [
-                                "exportKey(format: \"jwk\", key: CryptoKey): Promise<JsonWebKey>"
+                                "exportKey(format: \"jwk\", key: CryptoKey): Promise<JsonWebKey>",
+                                "exportKey(format: Exclude<KeyFormat, \"jwk\">, key: CryptoKey): Promise<ArrayBuffer>"
                             ],
                             "signature": {
                                 "0": {
                                     "param": [
                                         {
                                             "name": "format",
-                                            "overrideType": "Exclude<KeyFormat, \"jwk\">"
+                                            "overrideType": "KeyFormat"
                                         }
                                     ],
-                                    "overrideType": "Promise<ArrayBuffer>"
+                                    "overrideType": "Promise<ArrayBuffer | JsonWebKey>"
                                 }
                             }
                         },
diff --git a/unittests/files/keyusage.ts b/unittests/files/keyusage.ts
index fab5b4e94..7e037c4e6 100644
--- a/unittests/files/keyusage.ts
+++ b/unittests/files/keyusage.ts
@@ -1,15 +1,46 @@
-const usageInline = crypto.subtle.generateKey({
-  name: "AES-GCM",
-  length: 256,
-},  true, ['encrypt', 'decrypt'])
-
-const usageConst = crypto.subtle.generateKey( {
-  name: "AES-GCM",
-  length: 256,
-},  true, ['encrypt', 'decrypt'] as const)
-
-const keyUsage: ReadonlyArray<KeyUsage> = ['encrypt', 'decrypt']
-const usageAsReadonly = crypto.subtle.generateKey( {
-  name: "AES-GCM",
-  length: 256,
-},  true, keyUsage)
\ No newline at end of file
+function assertType<T>(_x: T) {}
+
+const mockKey = {} as CryptoKey;
+
+assertType<Promise<JsonWebKey>>(crypto.subtle.exportKey("jwk", mockKey));
+assertType<Promise<ArrayBuffer>>(crypto.subtle.exportKey("pkcs8", mockKey));
+assertType<Promise<ArrayBuffer>>(crypto.subtle.exportKey("raw", mockKey));
+assertType<Promise<ArrayBuffer>>(crypto.subtle.exportKey("spki", mockKey));
+
+assertType<Promise<ArrayBuffer | JsonWebKey>>(
+  crypto.subtle
+    .exportKey("" as KeyFormat, mockKey)
+    .then((ambiguousExportedKeyData) =>
+      ambiguousExportedKeyData instanceof ArrayBuffer
+        ? (ambiguousExportedKeyData satisfies ArrayBuffer)
+        : (ambiguousExportedKeyData satisfies JsonWebKey)
+    )
+);
+
+const usageInline = crypto.subtle.generateKey(
+  {
+    name: "AES-GCM",
+    length: 256,
+  },
+  true,
+  ["encrypt", "decrypt"]
+);
+
+const usageConst = crypto.subtle.generateKey(
+  {
+    name: "AES-GCM",
+    length: 256,
+  },
+  true,
+  ["encrypt", "decrypt"] as const
+);
+
+const keyUsage: ReadonlyArray<KeyUsage> = ["encrypt", "decrypt"];
+const usageAsReadonly = crypto.subtle.generateKey(
+  {
+    name: "AES-GCM",
+    length: 256,
+  },
+  true,
+  keyUsage
+);