diff --git a/src/types.d.ts b/src/types.d.ts
index bf675eba..739dfc32 100644
--- a/src/types.d.ts
+++ b/src/types.d.ts
@@ -164,7 +164,7 @@ export interface JWK {
  * @param token The consumed JWE or JWS token.
  */
 export interface GetKeyFunction<T, T2> {
-  (protectedHeader: T, token: T2): Promise<KeyLike | Uint8Array>
+  (protectedHeader: T, token: T2): Promise<KeyLike | Uint8Array> | KeyLike | Uint8Array
 }
 
 /**
diff --git a/test-deno/jwks.test.ts b/test-deno/jwks.test.ts
index 034d4d17..6ecdef13 100644
--- a/test-deno/jwks.test.ts
+++ b/test-deno/jwks.test.ts
@@ -10,12 +10,12 @@ Deno.test('fetches the JWKSet', async () => {
   const { alg, kid } = response.keys[0]
   const jwks = createRemoteJWKSet(new URL(jwksUri))
   await assertThrowsAsync(
-    () => jwks({ alg: 'RS256' }, <FlattenedJWSInput>{}),
+    async () => jwks({ alg: 'RS256' }, <FlattenedJWSInput>{}),
     errors.JWKSMultipleMatchingKeys,
     'multiple matching keys found in the JSON Web Key Set',
   )
   await assertThrowsAsync(
-    () => jwks({ kid: 'foo', alg: 'RS256' }, <FlattenedJWSInput>{}),
+    async () => jwks({ kid: 'foo', alg: 'RS256' }, <FlattenedJWSInput>{}),
     errors.JWKSNoMatchingKey,
     'no applicable key found in the JSON Web Key Set',
   )