diff --git a/README.md b/README.md
index 637eab3c..1b63a1ad 100644
--- a/README.md
+++ b/README.md
@@ -47,7 +47,7 @@
     <br/>
     <br/>
 - [**UI**](./docs/UI.md)
-  - [`useAudio`](./docs/useAudio.md) &mdash; plays audio and exposes its controls. [![][img-demo]](https://codesandbox.io/s/5v7q47knwl)
+  - [`useAudio`](./docs/useAudio.md) &mdash; plays audio and exposes its controls. [![][img-demo]](https://codesandbox.io/s/2o4lo6rqy)
   - [`useSpeech`](./docs/useSpeech.md) &mdash; synthesizes speech from a text string. [![][img-demo]](https://codesandbox.io/s/n090mqz69m)
   - [`useVideo`](./docs/useVideo.md) &mdash; plays video, tracks its state, and exposes playback controls.
     <br/>
diff --git a/src/useDropArea.ts b/src/useDropArea.ts
new file mode 100644
index 00000000..9710b709
--- /dev/null
+++ b/src/useDropArea.ts
@@ -0,0 +1,14 @@
+import * as React from 'react';
+
+const useDropArea = (el: React.ReactElement<any>) => {
+  if (process.env.NODE_ENV !== 'production') {
+    if (!React.isValidElement(el)) {
+      throw new TypeError(
+        'useDropArea first argument must be a valid ' +
+        'React element, such as <div/>.'
+      );
+    }
+  }
+};
+
+export default useDropArea;