diff --git a/docs/lib2-rand.md b/docs/lib2-rand.md
index dceef6c0..fac5d086 100644
--- a/docs/lib2-rand.md
+++ b/docs/lib2-rand.md
@@ -4,8 +4,8 @@ Random number generator. Generates a pseudo random number.
 
 ## Parameters
 
-- `min_value` : Minimum value of random number range.
-- `max_value` : Maximum value of random number range.
+- `min_value` : Minimum value of random number range. Default to 0.
+- `max_value` : Maximum value of random number range. Default to 1.
 - `seed_value` : Optional. Seed value for random number generator for repeatable results. 
 
 ## Examples