diff --git a/p2pool/sidechain/poolblock.go b/p2pool/sidechain/poolblock.go
index 4e89f2d..359ea0d 100644
--- a/p2pool/sidechain/poolblock.go
+++ b/p2pool/sidechain/poolblock.go
@@ -240,7 +240,7 @@ func NewShareFromExportedBytes(buf []byte, consensus *Consensus, cacheInterface
 	b.CachedShareVersion = b.CalculateShareVersion(consensus)
 
 	//TODO: this is to comply with non-standard p2pool serialization, see https://github.com/SChernykh/p2pool/issues/249
-	if t := b.Main.Coinbase.Extra.GetTag(transaction.TxExtraTagMergeMining); t == nil && t.VarInt != 32 {
+	if t := b.Main.Coinbase.Extra.GetTag(transaction.TxExtraTagMergeMining); t == nil || t.VarInt != 32 {
 		return nil, errors.New("wrong merge mining tag depth")
 	}
 
@@ -507,7 +507,7 @@ func (b *PoolBlock) FromReader(consensus *Consensus, derivationCache DerivationC
 	}
 
 	//TODO: this is to comply with non-standard p2pool serialization, see https://github.com/SChernykh/p2pool/issues/249
-	if t := b.Main.Coinbase.Extra.GetTag(transaction.TxExtraTagMergeMining); t == nil && t.VarInt != 32 {
+	if t := b.Main.Coinbase.Extra.GetTag(transaction.TxExtraTagMergeMining); t == nil || t.VarInt != 32 {
 		return errors.New("wrong merge mining tag depth")
 	}
 
@@ -533,7 +533,7 @@ func (b *PoolBlock) FromCompactReader(consensus *Consensus, derivationCache Deri
 	}
 
 	//TODO: this is to comply with non-standard p2pool serialization, see https://github.com/SChernykh/p2pool/issues/249
-	if t := b.Main.Coinbase.Extra.GetTag(transaction.TxExtraTagMergeMining); t == nil && t.VarInt != 32 {
+	if t := b.Main.Coinbase.Extra.GetTag(transaction.TxExtraTagMergeMining); t == nil || t.VarInt != 32 {
 		return errors.New("wrong merge mining tag depth")
 	}