diff --git a/bootstrap/lecture/permutecorrelation.py b/bootstrap/lecture/permutecorrelation.py
index 9b4d4f8..b6bc1bd 100644
--- a/bootstrap/lecture/permutecorrelation.py
+++ b/bootstrap/lecture/permutecorrelation.py
@@ -19,7 +19,7 @@ rd = np.corrcoef(x, y)[0, 1]
 # permutation:
 nperm = 1000
 rs = []
-for i in np.arange(nperm) :
+for i in range(nperm) :
     xr=rng.permutation(x)
     yr=rng.permutation(y)
     rs.append( np.corrcoef(xr, yr)[0, 1] )