diff --git a/python3.html.markdown b/python3.html.markdown
index b3acb122..f21604e4 100644
--- a/python3.html.markdown
+++ b/python3.html.markdown
@@ -591,6 +591,11 @@ math.sqrt(16) == m.sqrt(16)   # => True
 import math
 dir(math)
 
+# If you have a Python script named math.py in the same
+# folder as your current script, the file math.py will
+# be loaded instead of the built-in Python module.
+# This happens because the local folder has priority
+# over Python's built-in libraries.
 
 ####################################################
 ## 7. Advanced