diff --git a/docs/usage.md b/docs/usage.md
index 13dafe3..eeabf1c 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -1,7 +1,7 @@
 # NopSCADlib usage
 
 ## Requirements
-1. OpenSCAD 2019.05 or later, download it from here: https://www.openscad.org/downloads.html
+1. OpenSCAD 2021.01 or later, download it from here: https://www.openscad.org/downloads.html
 1. Python 2.7+ or 3.6+ from https://www.python.org/downloads/
 1. ImageMagick 7 www.imagemagick.org