diff --git a/core/tx_pool.go b/core/tx_pool.go
index 12dc2799a4..21fb5e5d0c 100644
--- a/core/tx_pool.go
+++ b/core/tx_pool.go
@@ -38,7 +38,7 @@ import (
 
 const (
 	// chainHeadChanSize is the size of channel listening to ChainHeadEvent.
-	chainHeadChanSize = 10
+	chainHeadChanSize = 9
 
 	// txSlotSize is used to calculate how many data slots a single transaction
 	// takes up based on its size. The slots are used as DoS protection, ensuring