diff --git a/doc/INSTALL b/doc/INSTALL
index 2213887fa..25a151641 100644
--- a/doc/INSTALL
+++ b/doc/INSTALL
@@ -7,7 +7,7 @@ http://www.redmine.org/
 
 == Requirements
 
-* Ruby >= 2.3
+* Ruby 2.3, 2.4, 2.5, 2.6
 * RubyGems
 * Bundler >= 1.5.0