diff --git a/bigchaindb/pipelines/block.py b/bigchaindb/pipelines/block.py
index 47fbd008..1d42423f 100644
--- a/bigchaindb/pipelines/block.py
+++ b/bigchaindb/pipelines/block.py
@@ -42,6 +42,7 @@ class Block:
 
         if tx['assignee'] == self.bigchain.me:
             tx.pop('assignee')
+            tx.pop('assignment_timestamp')
             return tx
 
     def delete_tx(self, tx):
diff --git a/tests/pipelines/test_block_creation.py b/tests/pipelines/test_block_creation.py
index 4abf72cc..a41f65b5 100644
--- a/tests/pipelines/test_block_creation.py
+++ b/tests/pipelines/test_block_creation.py
@@ -14,9 +14,14 @@ def test_filter_by_assignee(b, user_vk):
     tx = b.create_transaction(b.me, user_vk, None, 'CREATE')
     tx = b.sign_transaction(tx, b.me_private)
     tx['assignee'] = b.me
+    tx['assignment_timestamp'] = 111
 
     # filter_tx has side effects on the `tx` instance by popping 'assignee'
-    assert block_maker.filter_tx(tx) == tx
+    # and 'assignment_timestamp'
+    filtered_tx = block_maker.filter_tx(tx)
+    assert filtered_tx == tx
+    assert 'assignee' not in filtered_tx
+    assert 'assignment_timestamp' not in filtered_tx
 
     tx = b.create_transaction(b.me, user_vk, None, 'CREATE')
     tx = b.sign_transaction(tx, b.me_private)
@@ -116,6 +121,7 @@ def test_full_pipeline(b, user_vk):
         tx = b.sign_transaction(tx, b.me_private)
         assignee = random.choice([b.me, 'aaa', 'bbb', 'ccc'])
         tx['assignee'] = assignee
+        tx['assignment_timestamp'] = time.time()
         if assignee == b.me:
             count_assigned_to_me += 1
         r.table('backlog').insert(tx, durability='hard').run(b.conn)