diff --git a/README.md b/README.md
index 66b5325..f725bbb 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@
 ## Installation
 
 First, make sure that the latest `trezorlib` Python package
-is installed correctly:
+is installed correctly (at least v0.6.6):
 
 	$ pip install Cython trezor