diff --git a/source/simulation2/components/CCmpWaterManager.cpp b/source/simulation2/components/CCmpWaterManager.cpp
index e3a95ce403..c43a95a522 100644
--- a/source/simulation2/components/CCmpWaterManager.cpp
+++ b/source/simulation2/components/CCmpWaterManager.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2017 Wildfire Games.
+/* Copyright (C) 2021 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -55,6 +55,9 @@ public:
 
 	virtual void Deinit()
 	{
+		// Clear the map size & data.
+		if (CRenderer::IsInitialised())
+			g_Renderer.GetWaterManager()->SetMapSize(0);
 	}
 
 	virtual void Serialize(ISerializer& serialize)