diff --git a/README.rdoc b/README.rdoc
index 78afbc34..ff6fbe60 100644
--- a/README.rdoc
+++ b/README.rdoc
@@ -14,7 +14,7 @@
 
 == Requirement
 
-  *  Ruby 1.8.x or later.
+  *  Ruby 2.5 or later.
 
 == Installation