diff --git a/README.md b/README.md
index cc048d2..813499b 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@ Thanks to [@liuyao12](https://github.com/liuyao12) for the initial version of th
 npm install function-plot
 ```
 
-## Examples
+## Usage
 
 ```javascript
 import functionPlot from 'function-plot'
diff --git a/package-lock.json b/package-lock.json
index 9160b5a..bcfc6f1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -19,6 +19,7 @@
         "d3-selection": "^3.0.0",
         "d3-shape": "^3.1.0",
         "d3-zoom": "^3.0.0",
+        "events": "^3.3.0",
         "interval-arithmetic-eval": "^0.5.1"
       },
       "devDependencies": {
@@ -9812,7 +9813,6 @@
       "version": "3.3.0",
       "resolved": "https://registry.npmjs.org/events/-/events-3.3.0.tgz",
       "integrity": "sha512-mQw+2fkQbALzQ7V0MY0IqdnXNOeTtP4r0lN9z7AAawCXgqea7bDii20AYrIBrFd/Hx0M2Ocz6S111CaFkUcb0Q==",
-      "dev": true,
       "engines": {
         "node": ">=0.8.x"
       }
diff --git a/package.json b/package.json
index 8bdd01f..cf7b172 100644
--- a/package.json
+++ b/package.json
@@ -58,6 +58,7 @@
     "d3-selection": "^3.0.0",
     "d3-shape": "^3.1.0",
     "d3-zoom": "^3.0.0",
+    "events": "^3.3.0",
     "interval-arithmetic-eval": "^0.5.1"
   },
   "devDependencies": {