diff --git a/proofow.py b/proofow.py
index 4793f3a..5c049a5 100644
--- a/proofow.py
+++ b/proofow.py
@@ -4,8 +4,8 @@ from hashlib import sha256
 
 
 class proofow:
-    def __init__(self, difficulty):
-        self._base = urandom(32)
+    def __init__(self, difficulty, base=None):
+        self._base = urandom(32) if not base else base
         self._target = 2 ** (256 - difficulty)
 
     def work(self):