diff --git a/backend/nft_market/contracts/assets/manager.py b/backend/nft_market/contracts/assets/manager.py
index 9159e08..12575f3 100644
--- a/backend/nft_market/contracts/assets/manager.py
+++ b/backend/nft_market/contracts/assets/manager.py
@@ -36,6 +36,7 @@ def on_bid(self):
         prev_bid = ScratchSlot()
         return Seq(
             [
+                is_valid_tx.store(Int(0)),
                 prev_bid.store(self.bid_price.get()),
                 # Increase bid_price
                 If(