diff --git a/src/map.rs b/src/map.rs
index 2d78c7b..d8c32be 100644
--- a/src/map.rs
+++ b/src/map.rs
@@ -45,6 +45,9 @@ struct MapColors (Vec<[f32; 4]>);
 #[derive(Component)]
 pub struct CellsEntities (Vec<Entity>);
 
+#[derive(Component)]
+pub struct MeshNeedsUpdate(bool);
+
 fn setup(
     mut cmds: Commands,
     mut meshes: ResMut<Assets<Mesh>>,
@@ -134,17 +137,21 @@ fn setup(
         Transform::default(),
         Voronoi(voronoi),
         MapColors(colors),
+        MeshNeedsUpdate(true),
         MapMarker
     )).with_children(|parent| {
         for cd in cells_data {
             let mut cmd = parent.spawn((cd, LastUpdate(0)));
-            cmd.observe(|trigger: Trigger<Pointer<Click>>, mut cells: Query<&mut CellData>| {
+            cmd.observe(|trigger: Trigger<Pointer<Click>>, mut cells: Query<&mut CellData>, mut map_needs_update: Query<&mut MeshNeedsUpdate, With<MapMarker>>| {
                 if trigger.duration > Duration::from_millis(100) {
                     return
                 }
                 let mut cd = cells.get_mut(trigger.target).unwrap();
                 match cd.kind {
-                    CellKind::Dirt | CellKind::Grass => {cd.kind = CellKind::Forest;},
+                    CellKind::Dirt | CellKind::Grass => {
+                        cd.kind = CellKind::Forest;
+                        map_needs_update.single_mut().0 = true;
+                    },
                     _ => {}
                 }
                 dbg!(trigger.duration);
@@ -159,8 +166,10 @@ fn setup(
 pub struct LastUpdate(usize);
 
 fn update_cells(
-    mut cells: Query<(&mut CellData, &mut LastUpdate)>
+    mut cells: Query<(&mut CellData, &mut LastUpdate)>,
+    mut map_needs_update: Query<&mut MeshNeedsUpdate, With<MapMarker>>
 ) {
+    let mut map_needs_update = map_needs_update.single_mut();
     for (mut cd, mut lu) in cells.iter_mut() {
         lu.0 += 1;
         if lu.0 > match cd.kind {
@@ -170,27 +179,31 @@ fn update_cells(
         } {
             lu.0 = 0;
             cd.resource = (cd.resource + 1).clamp(0, 4);
+            map_needs_update.0 = true;
         }
     }
 }
 
 fn update_map_mesh(
     cells: Query<&CellData>,
-    mut map: Query<(&Mesh2d, &mut MapColors), With<MapMarker>>,
+    mut map: Query<(&Mesh2d, &mut MapColors, &mut MeshNeedsUpdate), With<MapMarker>>,
     mut meshes: ResMut<Assets<Mesh>>
 ) {
-    let (mesh, mut cols) = map.single_mut();
-    if let Some(mesh) = meshes.get_mut(mesh) {
-        let mut modified = false;
-        for cd in cells.iter() {
-            let col = cd.color();
-            for id in cd.vertices.iter() {
-                modified = modified || cols.0[*id] != col;
-                cols.0[*id] = col.clone();
+    let (mesh, mut cols, mut needs_update) = map.single_mut();
+    if needs_update.0 {
+        if let Some(mesh) = meshes.get_mut(mesh) {
+            let mut modified = false;
+            for cd in cells.iter() {
+                let col = cd.color();
+                for id in cd.vertices.iter() {
+                    modified = modified || cols.0[*id] != col;
+                    cols.0[*id] = col.clone();
+                }
+            }
+            if modified {
+                mesh.insert_attribute(Mesh::ATTRIBUTE_COLOR, cols.0.clone());
             }
         }
-        if modified {
-            mesh.insert_attribute(Mesh::ATTRIBUTE_COLOR, cols.0.clone());
-        }
+        needs_update.0 = false;
     }
 }
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