diff --git a/core/blockchain.go b/core/blockchain.go
index 9c7f75985a..7ad022f4f6 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -62,7 +62,7 @@ const (
 
 	// BlockChainVersion ensures that an incompatible database forces a resync from scratch.
 	BlockChainVersion = 3
-	M1Gap             = 3
+	M1Gap             = 5
 )
 
 // CacheConfig contains the configuration values for the trie caching/pruning