Index: source/simulation2/components/CCmpPathfinder.cpp
===================================================================
--- source/simulation2/components/CCmpPathfinder.cpp
+++ source/simulation2/components/CCmpPathfinder.cpp
@@ -552,6 +552,16 @@
 
 		SAFE_DELETE(m_TerrainOnlyGrid);
 		m_TerrainOnlyGrid = new Grid<NavcellData>(m_MapSize * Pathfinding::NAVCELLS_PER_TILE, m_MapSize * Pathfinding::NAVCELLS_PER_TILE);
+
+		// If this update comes from a map resizing, we must reinitialize the other grids as well
+		if (!m_TerrainOnlyGrid->compare_sizes(m_Grid))
+		{
+			SAFE_DELETE(m_Grid);
+			m_Grid = new Grid<NavcellData>(m_MapSize * Pathfinding::NAVCELLS_PER_TILE, m_MapSize * Pathfinding::NAVCELLS_PER_TILE);
+
+			m_DirtinessInformation = { true, true, Grid<u8>(m_MapSize * Pathfinding::NAVCELLS_PER_TILE, m_MapSize * Pathfinding::NAVCELLS_PER_TILE) };
+			m_AIPathfinderDirtinessInformation = m_DirtinessInformation;
+		}
 	}
 
 	Grid<u16> shoreGrid = ComputeShoreGrid();
Index: source/simulation2/helpers/Grid.h
===================================================================
--- source/simulation2/helpers/Grid.h
+++ source/simulation2/helpers/Grid.h
@@ -165,7 +165,7 @@
 	template<typename U>
 	bool compare_sizes(const Grid<U>* g) const
 	{
-		return m_W == g->m_W && m_H == g->m_H;
+		return g && m_W == g->m_W && m_H == g->m_H;
 	}
 
 	u16 m_W, m_H;