diff --git a/minode/proofofwork.py b/minode/proofofwork.py
index c878b2a..4a63b0a 100644
--- a/minode/proofofwork.py
+++ b/minode/proofofwork.py
@@ -19,8 +19,13 @@ def _pow_worker(target, initial_hash, q):
 
     while trial_value > target:
         nonce += 1
-        trial_value = struct.unpack('>Q', hashlib.sha512(hashlib.sha512(
-            struct.pack('>Q', nonce) + initial_hash).digest()).digest()[:8])[0]
+        try:
+            trial_value = struct.unpack('>Q', hashlib.sha512(hashlib.sha512(
+                struct.pack('>Q', nonce) + initial_hash
+            ).digest()).digest()[:8])[0]
+        except KeyboardInterrupt:
+            q.put(None)
+            return
 
     q.put(struct.pack('>Q', nonce))
 
@@ -36,6 +41,11 @@ def _worker(obj):
     nonce = q.get()
     p.join()
 
+    if nonce is None:
+        if not shared.shutting_down:
+            logging.warning('Got None nonce from _pow_worker!')
+        return
+
     logging.debug(
         'Finished doing POW, nonce: %s, time: %ss', nonce, time.time() - t)
     obj = structure.Object(