2 files changed, 6 insertions, 1 deletions

diff --git a/beamer/viewer/viewer.js b/beamer/viewer/viewer.js
index e9c6d65..a614c88 100644
--- a/beamer/viewer/viewer.js
+++ b/beamer/viewer/viewer.js
@@ -26,9 +26,14 @@ class Viewer {
     this.fileReader = new FileReader();
     this.presentation = null;
 
+    document.addEventListener("DOMContentLoaded", () => this._unlockUi());
     this._listenForInput();
   }
 
+  _unlockUi() {
+    this.fileInput.disabled = false;
+  }
+
   _preparePresentation(source) {
     const self = this;
     pdfjsLib.getDocument(source).then(function(pdf) {
diff --git a/index.html b/index.html
index f92f772..7259fe9 100644
--- a/index.html
+++ b/index.html
@@ -70,7 +70,7 @@
           <a href="#file=sample/demo.pdf" onclick="load('sample/demo.pdf')">demo slides</a>.
         </p>
 
-        <input id="fileInput" type="file" multiple="false" accept="application/pdf" />
+        <input id="fileInput" type="file" multiple="false" accept="application/pdf" disabled />
         <br />
         <br />
         <input id="startButton" type="button" value="Start presentation" disabled />