diff --git a/notebook.py b/notebook.py
index 7f0306335..a18282483 100644
--- a/notebook.py
+++ b/notebook.py
@@ -1061,7 +1061,7 @@ def plot_NQueens(solution):
     board = np.array([2 * int((i + j) % 2) for j in range(n) for i in range(n)]).reshape((n, n))
     im = Image.open('images/queen_s.png')
     height = im.size[1]
-    im = np.array(im).astype(np.float) / 255
+    im = np.array(im).astype(np.float64) / 255
     fig = plt.figure(figsize=(7, 7))
     ax = fig.add_subplot(111)
     ax.set_title('{} Queens'.format(n))
diff --git a/notebook4e.py b/notebook4e.py
index 5b03081c6..afb797d41 100644
--- a/notebook4e.py
+++ b/notebook4e.py
@@ -1097,7 +1097,7 @@ def plot_NQueens(solution):
     board = np.array([2 * int((i + j) % 2) for j in range(n) for i in range(n)]).reshape((n, n))
     im = Image.open('images/queen_s.png')
     height = im.size[1]
-    im = np.array(im).astype(np.float) / 255
+    im = np.array(im).astype(np.float64) / 255
     fig = plt.figure(figsize=(7, 7))
     ax = fig.add_subplot(111)
     ax.set_title('{} Queens'.format(n))