diff --git a/Chapter07/in_region_cost_example.py b/Chapter07/in_region_cost_example.py
index dac05c047bdb26eb6c862b3c14c468efa7fc8c41..929a2ea3b1c1efe3da9991e524a29b820e23d71a 100755
--- a/Chapter07/in_region_cost_example.py
+++ b/Chapter07/in_region_cost_example.py
@@ -4,6 +4,7 @@ import skimage.io
 import slgbuilder
 
 # This is to fix deprecated alias in numpy, but still used in slgbuilder
+# You need to add it to any script using (this version of) slgbuilder
 np.bool = bool
 np.int = int