diff --git a/Interface/grid_draw.py b/Interface/grid_draw.py
index ab878a2..5335dee 100644
--- a/Interface/grid_draw.py
+++ b/Interface/grid_draw.py
@@ -53,7 +53,7 @@ class GridDraw:
             self.line(0, tiles_height * i, self.width, tiles_height * i, color=color)
 
     @default_color
-    def circle(self, x, y, color=None):
+    def circle(self, x, y, radius, color=None):
         pygame.draw.circle(
-            self.screen, color, (x, y), 20
+            self.screen, color, (x, y), radius
         )  # TODO calculate radius (now 20) in terms of window size.
diff --git a/Interface/vacuum_render.py b/Interface/vacuum_render.py
index 7de34a4..b5007fe 100644
--- a/Interface/vacuum_render.py
+++ b/Interface/vacuum_render.py
@@ -16,18 +16,19 @@ def initial_draw(grid_dimensions, board_size):
     grid_height = grid_dimensions
 
     # FIXME @countingthedots: please tell me what is going on there and why???
+    # 
     grid = GridDraw(grid_width, grid_height)
     tile_width = grid_width / board_size
     tile_height = grid_height / board_size
     x = tile_width / 2
     y = tile_height / 2
-    radius = 20
+    radius = tile_height/3
 
     # rendering loop
     while True:
         grid.start_draw()
         grid.board(board_size, board_size)
         (x, y) = robot_movement(grid_width, grid_height, tile_width, tile_height, x, y)
-        grid.circle(x, y, color=Colors.RED)
+        grid.circle(x, y, radius, color=Colors.RED)
         grid.end_draw()
         pygame.time.delay(10)