diff --git a/cookbook/c03/p07_inf_nan.py b/cookbook/c03/p07_inf_nan.py
index 322033e..3516aea 100644
--- a/cookbook/c03/p07_inf_nan.py
+++ b/cookbook/c03/p07_inf_nan.py
@@ -16,7 +16,7 @@ def inf_nan():
     print(a * 10 == a)
     print(10 / a)
 
-    # undifined
+    # undefined
     print(a / a)
     print(a + b)