diff --git a/bingo/__init__.py b/bingo/__init__.py
index f7beb86..c94fa6a 100644
--- a/bingo/__init__.py
+++ b/bingo/__init__.py
@@ -3,12 +3,13 @@ import random
 class Board:
     def __init__(self):
         self.cols = []
+        self.called = []
         for col in range(5):
             n = 4 if col == 2 else 5
             self.cols.append(random.sample(range(15 * col + 1, 15 * col + 15), n))
+            self.called.append([False] * 5)
         self.cols[2][2:2] = [0]
         self.border = "+----" * 5 + "+"
-        self.called = {0}
 
     def print(self):
         for row in range(5):
@@ -18,10 +19,13 @@ class Board:
                 caption = self.cols[col][row]
                 if caption == 0:
                     caption = "F"
-                called = "*" if self.cols[col][row] in self.called else " "
+                called = "*" if self.called[col][row] else " "
                 print("|%s%2s%s" % (called, caption, called), end = "")
             print("|")
             print(self.border)
 
     def call(self, n):
-        self.called.add(n)
+        for col in range(5):
+            for row in range(5):
+                if self.cols[col][row] == n:
+                    self.called[col][row] = True