diff --git a/src/main/java/com/googlesource/gerrit/plugins/branchnetwork/canvas/GitGraphServlet.java b/src/main/java/com/googlesource/gerrit/plugins/branchnetwork/canvas/GitGraphServlet.java
index 52b34ad..495352e 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/branchnetwork/canvas/GitGraphServlet.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/branchnetwork/canvas/GitGraphServlet.java
@@ -74,6 +74,7 @@
   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse resp)
       throws ServletException, IOException {
+    resp.setContentType("text/html;charset=UTF-8");
     PrintWriter out = resp.getWriter();
 
     try {