diff --git a/src/rfc3161_client/tsp.py b/src/rfc3161_client/tsp.py
index 2f5d839..5d1dd74 100644
--- a/src/rfc3161_client/tsp.py
+++ b/src/rfc3161_client/tsp.py
@@ -165,7 +165,7 @@ def ordering(self) -> bool:
 
     @property
     @abc.abstractmethod
-    def nonce(self) -> bytes:
+    def nonce(self) -> int:
         """Returns the nonce."""
 
     @property