diff --git a/src/game.rs b/src/game.rs
index 903fe7d..8408ec4 100644
--- a/src/game.rs
+++ b/src/game.rs
@@ -39,6 +39,7 @@ pub enum GameState {
     Placing,
     Removing,
     Main,
+    Won(PlayerColor),
 }
 
 #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone, Copy)]
@@ -453,6 +454,7 @@ impl MillGame {
 
             match *state {
                 GameState::Placing => {
+                    // check if all stones are placed
                     if !self
                         .black_stones
                         .lock()
@@ -473,6 +475,7 @@ impl MillGame {
                     self.current_player.lock().unwrap().swap();
                 }
                 GameState::Removing => {
+                    // check if all stones are placed, then decide whether main or placing is next state
                     if !self
                         .black_stones
                         .lock()
@@ -496,9 +499,39 @@ impl MillGame {
                     self.current_player.lock().unwrap().swap();
                 }
                 GameState::Main => {
+                    // check if each player has enough stones to play
+                    if self
+                        .white_stones
+                        .lock()
+                        .unwrap()
+                        .iter()
+                        .filter(|stone| stone.state != StoneState::Dead)
+                        .collect::<Vec<&Stone>>()
+                        .len()
+                        <= 3
+                    {
+                        *state = GameState::Won(PlayerColor::Black);
+                        return Ok(());
+                    }
+
+                    if self
+                        .black_stones
+                        .lock()
+                        .unwrap()
+                        .iter()
+                        .filter(|stone| stone.state != StoneState::Dead)
+                        .collect::<Vec<&Stone>>()
+                        .len()
+                        <= 3
+                    {
+                        *state = GameState::Won(PlayerColor::White);
+                        return Ok(());
+                    }
+
                     self.current_player.lock().unwrap().swap();
                 }
                 GameState::Waiting => unreachable!(),
+                GameState::Won(_) => (),
             }
         }
 
@@ -1059,7 +1092,7 @@ impl EngineObject for MillGame {
                                     Ok(())
                                 })?;
                             }
-                            GameState::Waiting => (),
+                            GameState::Waiting | GameState::Won(_) => (),
                         }
                     }
                     MouseButton::Middle => self.camera_controls.lock().unwrap().hold(),
diff --git a/src/simple_ai.rs b/src/simple_ai.rs
index cdd84a7..8e15f0c 100644
--- a/src/simple_ai.rs
+++ b/src/simple_ai.rs
@@ -166,6 +166,7 @@ impl SimpleAI {
                 })?;
             }
             GameState::Waiting => unreachable!(),
+            GameState::Won(_) => (),
         }
 
         if found_a_mill {