diff --git a/cli/tests/unit/webcrypto_test.ts b/cli/tests/unit/webcrypto_test.ts
index 493cf95172..1c4788f87d 100644
--- a/cli/tests/unit/webcrypto_test.ts
+++ b/cli/tests/unit/webcrypto_test.ts
@@ -536,3 +536,24 @@ unitTest(async function testWrapKey() {
   assert(wrappedKey instanceof ArrayBuffer);
   assertEquals(wrappedKey.byteLength, 512);
 });
+
+// Doesn't need to cover all cases.
+// Only for testing types.
+unitTest(async function testAesKeyGen() {
+  const key = await crypto.subtle.generateKey(
+    {
+      name: "AES-GCM",
+      length: 256,
+    },
+    true,
+    ["encrypt", "decrypt"],
+  );
+
+  assert(key);
+  assertEquals(key.type, "secret");
+  assertEquals(key.extractable, true);
+  assertEquals(key.usages, ["encrypt", "decrypt"]);
+  const algorithm = key.algorithm as AesKeyAlgorithm;
+  assertEquals(algorithm.name, "AES-GCM");
+  assertEquals(algorithm.length, 256);
+});
diff --git a/ext/crypto/lib.deno_crypto.d.ts b/ext/crypto/lib.deno_crypto.d.ts
index 3dd66d59a3..673e8f9cb8 100644
--- a/ext/crypto/lib.deno_crypto.d.ts
+++ b/ext/crypto/lib.deno_crypto.d.ts
@@ -125,6 +125,14 @@ interface Pbkdf2Params extends Algorithm {
   salt: BufferSource;
 }
 
+interface AesKeyGenParams extends Algorithm {
+  length: number;
+}
+
+interface AesKeyAlgorithm extends KeyAlgorithm {
+  length: number;
+}
+
 /** The CryptoKey dictionary of the Web Crypto API represents a cryptographic key. */
 interface CryptoKey {
   readonly algorithm: KeyAlgorithm;
@@ -157,7 +165,7 @@ interface SubtleCrypto {
     keyUsages: KeyUsage[],
   ): Promise<CryptoKeyPair>;
   generateKey(
-    algorithm: HmacKeyGenParams,
+    algorithm: AesKeyGenParams | HmacKeyGenParams,
     extractable: boolean,
     keyUsages: KeyUsage[],
   ): Promise<CryptoKey>;