diff --git a/web3/_utils/transactions.py b/web3/_utils/transactions.py
index c48d1a2024..a6a896f0ab 100644
--- a/web3/_utils/transactions.py
+++ b/web3/_utils/transactions.py
@@ -65,7 +65,11 @@ def wait_for_transaction_receipt(web3, txn_hash, timeout=120, poll_latency=0.1):
     with Timeout(timeout) as _timeout:
         while True:
             txn_receipt = web3.eth.getTransactionReceipt(txn_hash)
-            if txn_receipt is not None:
+            # FIXME: The check for a null `blockHash` is due to parity's
+            # non-standard implementation of the JSON-RPC API and should
+            # be removed once the formal spec for the JSON-RPC endpoints
+            # has been finalized.
+            if txn_receipt is not None and txn_receipt['blockHash'] is not None:
                 break
             _timeout.sleep(poll_latency)
     return txn_receipt