diff --git a/src/pool_block.cpp b/src/pool_block.cpp
index a2d6bff..c24dcc0 100644
--- a/src/pool_block.cpp
+++ b/src/pool_block.cpp
@@ -416,7 +416,14 @@ bool PoolBlock::merge_mining_enabled() const
 #ifdef P2POOL_UNIT_TESTS
 	return false;
 #else
-	return (SideChain::network_type() != NetworkType::Mainnet) || (m_timestamp >= MERGE_MINING_FORK_TIME);
+	switch (SideChain::network_type()) {
+	case NetworkType::Mainnet:
+		return m_timestamp >= MERGE_MINING_FORK_TIME;
+	case NetworkType::Testnet:
+		return m_timestamp >= MERGE_MINING_TESTNET_FORK_TIME;
+	default:
+		return false;
+	}
 #endif
 }
 
diff --git a/src/pool_block.h b/src/pool_block.h
index 8322b0c..0361fce 100644
--- a/src/pool_block.h
+++ b/src/pool_block.h
@@ -60,8 +60,11 @@ static constexpr difficulty_type MAX_CUMULATIVE_DIFFICULTY{ 13019633956666736640
 // 1000 years at 1 block/second. It should be enough for any normal use.
 static constexpr uint64_t MAX_SIDECHAIN_HEIGHT = 31556952000ULL;
 
-// Jul 01 2024 00:00:00 GMT+0000
-static constexpr uint64_t MERGE_MINING_FORK_TIME = 1719792000;
+// TBD
+static constexpr uint64_t MERGE_MINING_FORK_TIME = std::numeric_limits<uint64_t>::max();
+
+// Jun 09 2024 20:00:00 GMT+0000
+static constexpr uint64_t MERGE_MINING_TESTNET_FORK_TIME = 1717963200;
 
 struct DifficultyData
 {