diff --git a/README.md b/README.md
index ef8988d..2988cd4 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ This repository provides three folders for each compilation.
 2. ```proto```: Source file
 3. ```js```: Result file
 
-The tools used for compilation is called
+The tool used for compilation is called
 [pbf](https://github.com/mapbox/pbf)
 and installed in a global fashion like this.
 ```