diff --git a/README.adoc b/README.adoc
index 427ff9e..7a56ada 100644
--- a/README.adoc
+++ b/README.adoc
@@ -13,6 +13,7 @@ endif::[]
 
 - Python >= 3.6.5
 - pygame >= 1.9.3
+- tkinter (must be installed on system, see http://www.tkdocs.com/tutorial/install.html[the docs])
 - pipenv (for dependencies management)
 
 === Install dependencies