diff --git a/README.md b/README.md
index 126a9ec7..0f9aeba3 100644
--- a/README.md
+++ b/README.md
@@ -129,7 +129,7 @@ task default: 'bundle:audit'
 
 * [ruby] >= 1.9.3
 * [rubygems] >= 1.8
-* [thor] ~> 0.18
+* [thor] >= 0.18, < 2
 * [bundler] ~> 1.2
 
 ## Install