diff --git a/README.md b/README.md
index d20df74..ae5983b 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ Table of Contents
 
 ## Requirements
 - Ruby > 2.0
-- Doorkeeper > 1.4.0 and < 4.0
+- Doorkeeper > 1.4.0 and <= 4.0
 - Grape > 0.10 and < 1.0
 Please submit pull requests and Travis env bumps for newer dependency versions.