diff --git a/runner/index.html b/runner/index.html
index 9a1e765..966dede 100644
--- a/runner/index.html
+++ b/runner/index.html
@@ -1,5 +1,6 @@
 <html>
 <head>
+  <meta charset="UTF-8">
   <script>
     // Check for wasm support.
     if (!('WebAssembly' in window)) {
