diff --git a/lib/goban.py b/lib/goban.py
index ba7e770..311ffc5 100644
--- a/lib/goban.py
+++ b/lib/goban.py
@@ -180,7 +180,7 @@ class Goban:
             self.white_captures += captures
 
         # Check for ko
-        if captures == 1 and self._num_liberties(pos, color):
+        if captures == 1 and self._num_liberties(pos, color) == 1:
             # find the empty point
             for p in self._neighbors(pos):
                 if self.board[p] == Goban.EMPTY: