diff --git a/chess/__init__.py b/chess/__init__.py
index b51c31ca..347f22ea 100644
--- a/chess/__init__.py
+++ b/chess/__init__.py
@@ -916,7 +916,7 @@ def king(self, color: Color) -> Optional[Square]:
         considered.
         """
         king_mask = self.occupied_co[color] & self.kings & ~self.promoted
-        return msb(king_mask) if king_mask else None
+        return msb(king_mask) if king_mask and popcount(king_mask) == 1 else None
 
     def attacks_mask(self, square: Square) -> Bitboard:
         bb_square = BB_SQUARES[square]
diff --git a/test.py b/test.py
index 2ebd357d..4927a2b8 100755
--- a/test.py
+++ b/test.py
@@ -1720,6 +1720,10 @@ def test_impossible_check_due_to_en_passant(self):
         self.assertFalse(board.has_legal_en_passant())
         self.assertEqual(len(list(board.legal_moves)), 2)
 
+    def test_multiple_kings(self):
+        board = chess.Board("KKKK1kkk/8/8/8/8/8/8/8 w - - 0 1")
+        self.assertEqual(board.king(chess.WHITE), None)
+
 
 class LegalMoveGeneratorTestCase(unittest.TestCase):