diff --git a/source/network/FSM.cpp b/source/network/FSM.cpp
index d2e8e5184d..fdca70eb66 100644
--- a/source/network/FSM.cpp
+++ b/source/network/FSM.cpp
@@ -50,7 +50,6 @@ void CFsm::Setup()
 
 void CFsm::Shutdown()
 {
-	m_States.clear();
 	m_Transitions.clear();
 
 	m_Done = false;
@@ -59,20 +58,9 @@ void CFsm::Shutdown()
 	m_NextState = FSM_INVALID_STATE;
 }
 
-void CFsm::AddState(unsigned int state)
-{
-	m_States.insert(state);
-}
-
 void CFsm::AddTransition(unsigned int state, unsigned int eventType, unsigned int nextState,
 	Action* pAction /* = nullptr */, void* pContext /* = nullptr*/)
 {
-	// Make sure we store the current state
-	AddState(state);
-
-	// Make sure we store the next state
-	AddState(nextState);
-
 	m_Transitions.insert({TransitionKey{state, eventType}, Transition{{pAction, pContext}, nextState}});
 }
 
@@ -96,9 +84,6 @@ bool CFsm::Update(unsigned int eventType, void* pEventParam)
 	if (IsFirstTime())
 		m_CurrState = m_FirstState;
 
-	if (!IsValidState(m_CurrState))
-		return false;
-
 	// Lookup transition
 	auto transitionIterator = m_Transitions.find({m_CurrState, eventType});
 	if (transitionIterator == m_Transitions.end())
@@ -126,12 +111,3 @@ bool CFsm::IsDone() const
 	// By default the internal flag m_Done is tested
 	return m_Done;
 }
-
-bool CFsm::IsValidState(unsigned int state) const
-{
-	StateSet::const_iterator it = m_States.find(state);
-	if (it == m_States.end())
-		return false;
-
-	return true;
-}
diff --git a/source/network/FSM.h b/source/network/FSM.h
index fab678421b..482b54f88a 100644
--- a/source/network/FSM.h
+++ b/source/network/FSM.h
@@ -19,7 +19,6 @@
 #define FSM_H
 
 #include <limits>
-#include <set>
 #include <unordered_map>
 
 
@@ -41,8 +40,6 @@ struct CallbackFunction
 	}
 };
 
-using StateSet = std::set<unsigned int>;
-
 /**
  * Represents a signal in the state machine that a change has occurred.
  * The CFsmEvent objects are under the control of CFsm so
@@ -101,12 +98,6 @@ public:
 	 */
 	void Shutdown();
 
-	/**
-	 * Adds the specified state to the internal list of states.
-	 * @note If a state with the specified ID exists, the state is not added.
-	 */
-	void AddState(unsigned int state);
-
 	/**
 	 * Adds a new transistion to the state machine.
 	 */
@@ -137,22 +128,12 @@ public:
 		return m_NextState;
 	}
 
-	const StateSet& GetStates() const
-	{
-		return m_States;
-	}
-
 	/**
 	 * Updates the FSM and retrieves next state.
 	 * @return whether the state was changed.
 	 */
 	bool Update(unsigned int eventType, void* pEventData);
 
-	/**
-	 * Verifies whether the specified state is managed by the FSM.
-	 */
-	bool IsValidState(unsigned int state) const;
-
 	/**
 	 * Tests whether the state machine has finished its work.
 	 * @note This is state machine specific.
@@ -200,7 +181,6 @@ private:
 	unsigned int m_FirstState;
 	unsigned int m_CurrState;
 	unsigned int m_NextState;
-	StateSet m_States;
 	TransitionMap m_Transitions;
 };
 
diff --git a/source/network/NetServer.cpp b/source/network/NetServer.cpp
index 5e005e0744..72c206fefd 100644
--- a/source/network/NetServer.cpp
+++ b/source/network/NetServer.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2023 Wildfire Games.
+/* Copyright (C) 2024 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -48,6 +48,7 @@
 #include <miniupnpc/upnperrors.h>
 #endif
 
+#include <set>
 #include <string>
 
 /**