diff --git a/pyproject.toml b/pyproject.toml
index 062a1c5..aebc796 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "sw-utils"
-version = "v0.13.2"
+version = "v0.13.3"
 description = "StakeWise Python utils"
 authors = ["StakeWise Labs <info@stakewise.io>"]
 license = "GPL-3.0-or-later"
diff --git a/sw_utils/tests/factories.py b/sw_utils/tests/factories.py
index 46ce7e4..67bf1cd 100644
--- a/sw_utils/tests/factories.py
+++ b/sw_utils/tests/factories.py
@@ -21,6 +21,10 @@ def private_key(self) -> int:
         private_key = G2ProofOfPossession.KeyGen(seed)
         return private_key
 
+    def private_key_hex(self) -> HexStr:
+        # 32-byte private key as 0x-prefixed hex string
+        return Web3.to_hex(random.randbytes(32))
+
     def eth_address(self) -> ChecksumAddress:
         account = w3.eth.account.create()
         return account.address