diff --git a/src/pool_block_parser.inl b/src/pool_block_parser.inl
index 602c0d3..d5a4a12 100644
--- a/src/pool_block_parser.inl
+++ b/src/pool_block_parser.inl
@@ -61,21 +61,17 @@ int PoolBlock::deserialize(const uint8_t* data, size_t size, const SideChain& si
 
 #define READ_BUF(buf, size) do { if (!read_buf((buf), (size))) return __LINE__; } while(0)
 
-		if (!merge_mining_enabled()) {
-			READ_BYTE(m_majorVersion);
-			READ_BYTE(m_minorVersion);
-		}
-		else {
-			READ_VARINT(m_majorVersion);
-			READ_VARINT(m_minorVersion);
-		}
-
+		READ_BYTE(m_majorVersion);
 		if (m_majorVersion > HARDFORK_SUPPORTED_VERSION) return __LINE__;
+
+		READ_BYTE(m_minorVersion);
 		if (m_minorVersion < m_majorVersion) return __LINE__;
 
 		READ_VARINT(m_timestamp);
 		READ_BUF(m_prevId.h, HASH_SIZE);
 
+		if (merge_mining_enabled() && (m_minorVersion > 127)) return __LINE__;
+
 		const int nonce_offset = static_cast<int>(data - data_begin);
 		READ_BUF(&m_nonce, NONCE_SIZE);