diff --git a/src/windows/map.c b/src/windows/map.c
index e8fb28dc31..2f81c74f05 100644
--- a/src/windows/map.c
+++ b/src/windows/map.c
@@ -1349,12 +1349,6 @@ static void map_window_increase_map_size()
 	map_extend_boundary_surface();
 	window_map_init_map();
 	window_map_center_on_view_point();
-    // Recalculate fences
-	for (int y = 0; y < RCT2_GLOBAL(RCT2_ADDRESS_MAP_MAX_XY, uint16); y += 32) {
-		for (int x = 0; x < RCT2_GLOBAL(RCT2_ADDRESS_MAP_MAX_XY, uint16); x += 32) {
-			update_park_fences(x, y);
-		}
-	}
 	gfx_invalidate_screen();
 }
 
diff --git a/src/world/map.c b/src/world/map.c
index 5013ee1f55..495a8ef87b 100644
--- a/src/world/map.c
+++ b/src/world/map.c
@@ -4432,6 +4432,8 @@ void map_extend_boundary_surface()
 		newMapElement->properties.surface.slope |= slope;
 		newMapElement->base_height = z;
 		newMapElement->clearance_height = z;
+
+		update_park_fences(x << 5, y << 5);
 	}
 
 	x = RCT2_GLOBAL(RCT2_ADDRESS_MAP_SIZE, uint16) - 2;
@@ -4466,8 +4468,9 @@ void map_extend_boundary_surface()
 		newMapElement->properties.surface.slope |= slope;
 		newMapElement->base_height = z;
 		newMapElement->clearance_height = z;
-	}
 
+		update_park_fences(x << 5, y << 5);
+	}
 }
 
 /**