diff --git a/src/workprover/fastsolver/common.c b/src/workprover/fastsolver/common.c
index 91477154..cc381e5f 100644
--- a/src/workprover/fastsolver/common.c
+++ b/src/workprover/fastsolver/common.c
@@ -23,14 +23,14 @@ static void encode_big_endian(char *result, unsigned long long number) {
 
 static unsigned long long decode_big_endian(const char *encoded) {
     return (
-        (unsigned long long) encoded[0] << 56 |
-        (unsigned long long) encoded[1] << 48 |
-        (unsigned long long) encoded[2] << 40 |
-        (unsigned long long) encoded[3] << 32 |
-        (unsigned long long) encoded[4] << 24 |
-        (unsigned long long) encoded[5] << 16 |
-        (unsigned long long) encoded[6] << 8 |
-        (unsigned long long) encoded[7]
+        ((unsigned long long) encoded[0] & 0xff) << 56 |
+        ((unsigned long long) encoded[1] & 0xff) << 48 |
+        ((unsigned long long) encoded[2] & 0xff) << 40 |
+        ((unsigned long long) encoded[3] & 0xff) << 32 |
+        ((unsigned long long) encoded[4] & 0xff) << 24 |
+        ((unsigned long long) encoded[5] & 0xff) << 16 |
+        ((unsigned long long) encoded[6] & 0xff) << 8 |
+        ((unsigned long long) encoded[7] & 0xff)
     );
 }
 
diff --git a/src/workprover/test.py b/src/workprover/test.py
index bfc3fd3d..535f50ce 100755
--- a/src/workprover/test.py
+++ b/src/workprover/test.py
@@ -65,15 +65,16 @@ class TestUtils(unittest.TestCase):
         self.assertTrue(utils.checkProof(nonce, initialHash, 0x000002fe91eba356))
 
     def testCheckWorkSufficient(self):
+        self.assertFalse(utils.checkWorkSufficient(payload, byteDifficulty, lengthExtension, expiryTime - 293757.5))
+        self.assertTrue(utils.checkWorkSufficient(payload, byteDifficulty, lengthExtension, expiryTime - 293757))
+
         originalTime = utils.time.time
 
         utils.time.time = lambda: expiryTime - 293757.5
         self.assertFalse(utils.checkWorkSufficient(payload, byteDifficulty, lengthExtension))
-        self.assertFalse(utils.checkWorkSufficient(payload, byteDifficulty, lengthExtension, expiryTime - 293757.5))
 
         utils.time.time = lambda: expiryTime - 293757
         self.assertTrue(utils.checkWorkSufficient(payload, byteDifficulty, lengthExtension))
-        self.assertTrue(utils.checkWorkSufficient(payload, byteDifficulty, lengthExtension, expiryTime - 293757))
 
         utils.time.time = originalTime