diff --git a/README.md b/README.md
index cfb4d6b..13fd2f8 100644
--- a/README.md
+++ b/README.md
@@ -69,7 +69,7 @@ pip3 install ctmodbus
 > historian tcp:10.1.1.1:9300                     # transactions to cthistorian
 ```
 
-## This tool is built upon these to key library:
+## This tool is built upon these two key libraries:
 
 - [Control Things User Interface](https://github.com/ControlThingsTools/ctui)
 - [PyModbus](https://github.com/bashwork/pymodbus)