diff --git a/graphenebase/transactions.py b/graphenebase/transactions.py
index <HASH>..<HASH> 100644
--- a/graphenebase/transactions.py
+++ b/graphenebase/transactions.py
@@ -609,7 +609,7 @@ def getBlockParams(ws) :
         witness node!
     """
     dynBCParams = ws.get_object("2.1.0")
-    ref_block_num = dynBCParams["head_block_number"]
+    ref_block_num = dynBCParams["head_block_number"] & 0xFFFF
     ref_block_prefix = struct.unpack_from("<I", unhexlify(dynBCParams["head_block_id"]), 4)[0]
     return ref_block_num, ref_block_prefix
[Transactions] Fix ref_block_num by limiting to 0x<I>xffff