diff --git a/src/p2p_server.cpp b/src/p2p_server.cpp
index fa28889..a8c1a0b 100644
--- a/src/p2p_server.cpp
+++ b/src/p2p_server.cpp
@@ -760,6 +760,11 @@ void P2PServer::Peer::normalize()
 
 void P2PServer::broadcast(const PoolBlock& block, const PoolBlock* parent)
 {
+	// Don't broadcast blocks when shutting down
+	if (m_finished.load()) {
+		return;
+	}
+
 	MinerData miner_data = m_pool->miner_data();
 
 	if (block.m_txinGenHeight + 2 < miner_data.height) {
diff --git a/src/pool_block.h b/src/pool_block.h
index b95a283..4b538ed 100644
--- a/src/pool_block.h
+++ b/src/pool_block.h
@@ -54,6 +54,12 @@ static constexpr uint64_t MAX_BLOCK_SIZE = 128 * 1024 - 5;
 // 0.6 XMR
 static constexpr uint64_t BASE_BLOCK_REWARD = 600000000000ULL;
 
+// 1000 years at 1 TH/s. It should be enough for any normal use.
+static constexpr difficulty_type MAX_CUMULATIVE_DIFFICULTY{ 13019633956666736640ULL, 1710ULL };
+
+// 1000 years at 1 block/second. It should be enough for any normal use.
+static constexpr uint64_t MAX_SIDECHAIN_HEIGHT = 31556952000ULL;
+
 struct DifficultyData
 {
 	FORCEINLINE DifficultyData(uint64_t t, const difficulty_type& d) : m_timestamp(t), m_cumulativeDifficulty(d) {}
diff --git a/src/pool_block_parser.inl b/src/pool_block_parser.inl
index dd44e73..29eee72 100644
--- a/src/pool_block_parser.inl
+++ b/src/pool_block_parser.inl
@@ -326,12 +326,20 @@ int PoolBlock::deserialize(const uint8_t* data, size_t size, const SideChain& si
 
 		READ_VARINT(m_sidechainHeight);
 
+		if (m_sidechainHeight > MAX_SIDECHAIN_HEIGHT) {
+			return __LINE__;
+		}
+
 		READ_VARINT(m_difficulty.lo);
 		READ_VARINT(m_difficulty.hi);
 
 		READ_VARINT(m_cumulativeDifficulty.lo);
 		READ_VARINT(m_cumulativeDifficulty.hi);
 
+		if (m_cumulativeDifficulty > MAX_CUMULATIVE_DIFFICULTY) {
+			return __LINE__;
+		}
+
 		uint8_t merkle_proof_size;
 		READ_BYTE(merkle_proof_size);