diff --git a/README.md b/README.md
index 6f2ea4b..025db1a 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,8 @@ Commands added that **need** to be used in the preamble are:
 - `\professor{args}` to indicate the name of the professor,
 - `\class{args}` to indicate the course this homework is intended to be delivered.
 
+The default paper size is A4; this can be changed to Letter using `letterpaper` in the options of the class.
+
 Packages `geometry`, `inputenc`, `fancyhdr` and `titlesec` are required. Also, UTF-8 needs to be the encoding of the `.tex` file.
 
 The AMS packages need to be loaded in the preamble of the document.