diff --git a/CONTRIBUTING.txt b/CONTRIBUTING.txt
index 0fa66ddd..9b1df551 100644
--- a/CONTRIBUTING.txt
+++ b/CONTRIBUTING.txt
@@ -145,6 +145,7 @@ Stylistic Guidelines
 
    import numpy as np
    import matplotlib.pyplot as plt
+   from scipy import ndimage as ndi
 
    cimport numpy as cnp # in Cython code