diff --git a/src/index.d.ts b/src/index.d.ts
index 73f794f..1034bd8 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -66,7 +66,7 @@ type VerifierCallback = (e: Error | TokenError | null, payload: any) => void
 
 type DecodedJwt = {
   header: { [key: string]: any },
-  payload: string,
+  payload: any,
   signature: string
 }
 
diff --git a/test/types.spec.ts b/test/types.spec.ts
index f6c07f3..d0db95a 100644
--- a/test/types.spec.ts
+++ b/test/types.spec.ts
@@ -63,7 +63,10 @@ createVerifier({
 // Dynamic key in async style
 createVerifier({
   clockTimestamp: 10,
-  async key(_decodedJwt: DecodedJwt) {
+  async key(decodedJwt: DecodedJwt) {
+    if (decodedJwt.payload.iss) {
+      return 'ISS_KEY'
+    }
     return 'KEY'
   }
 })('456').then(console.log, console.log)