diff --git a/src/lib/sim/Simulation.cpp b/src/lib/sim/Simulation.cpp
index 17d14df..27140d2 100644
--- a/src/lib/sim/Simulation.cpp
+++ b/src/lib/sim/Simulation.cpp
@@ -48,32 +48,7 @@ Simulation::Simulation(GameConfig config, unsigned int seed)
     m_currentEnemyStationEntities[0] = entt::null;
     m_currentEnemyStationEntities[1] = entt::null;
 
-    m_buildingSystem = std::make_unique<BuildingSystem>(
-        m_config,
-        m_beltSystem,
-        [this]() { return allocateBuildingId(); },
-        [this](int amount) { m_buildingBlocksStock += amount; },
-        [this](const std::string& id, QVector2D pos,
-               const std::optional<ShipLayoutConfig>& layout) {
-            const std::map<std::string, SchematicState>::const_iterator it =
-                m_schematicLevels.find(id);
-            if (it == m_schematicLevels.end() || !it->second.unlocked)
-            {
-                return;
-            }
-            m_shipSystem->spawn(id, pos, /*isEnemy=*/false, layout);
-        },
-        [this](const std::string& itemId) -> bool { return isItemUnlocked(itemId); },
-        m_rng);
-    m_shipSystem     = std::make_unique<ShipSystem>(m_config, m_admin);
-    m_aiSystem       = std::make_unique<AiSystem>(m_config);
-    m_movementIntentSystem = std::make_unique<MovementIntentSystem>();
-    m_dynamicBodySystem    = std::make_unique<DynamicBodySystem>();
-    m_debrisSystem    = std::make_unique<DebrisSystem>(m_admin);
-    m_salvagerSystem = std::make_unique<SalvagerSystem>(m_admin);
-    m_repairSystem   = std::make_unique<RepairSystem>(m_admin);
-    m_waveSystem     = std::make_unique<WaveSystem>(m_config, m_rng);
-    m_combatSystem   = std::make_unique<CombatSystem>(m_config);
+    initializeSubsystems();
 
     initializeUnlockState();
     placeInitialStructures();
@@ -120,6 +95,14 @@ void Simulation::reset(unsigned int seed)
 
     m_admin.clear();
     m_beltSystem = BeltSystem(m_config.world.beltSpeed_tps);
+    initializeSubsystems();
+
+    initializeUnlockState();
+    placeInitialStructures();
+}
+
+void Simulation::initializeSubsystems()
+{
     m_buildingSystem = std::make_unique<BuildingSystem>(
         m_config,
         m_beltSystem,
@@ -146,9 +129,6 @@ void Simulation::reset(unsigned int seed)
     m_repairSystem   = std::make_unique<RepairSystem>(m_admin);
     m_waveSystem     = std::make_unique<WaveSystem>(m_config, m_rng);
     m_combatSystem   = std::make_unique<CombatSystem>(m_config);
-
-    initializeUnlockState();
-    placeInitialStructures();
 }
 
 void Simulation::initializeUnlockState()
diff --git a/src/lib/sim/Simulation.h b/src/lib/sim/Simulation.h
index 851787c..bacb185 100644
--- a/src/lib/sim/Simulation.h
+++ b/src/lib/sim/Simulation.h
@@ -165,6 +165,11 @@ private:
 
     BuildingId allocateBuildingId();  // Strictly increasing; never returns kInvalidBuildingId.
 
+    // (Re-)create every owned subsystem. Shared by the constructor and reset();
+    // the construction order is load-bearing for determinism, so both paths must
+    // go through here. Only called before the first tick of a run.
+    void initializeSubsystems();
+
     // Populate HQ, player defence stations, and the first enemy station set.
     void placeInitialStructures();