diff --git a/mandaye/mappers/default.py b/mandaye/mappers/default.py
index ab81a0f..ffa3e1f 100644
--- a/mandaye/mappers/default.py
+++ b/mandaye/mappers/default.py
@@ -19,7 +19,12 @@ if config.mandaye_toolbar:
     mapping.extend([
         {
             'path': r'/',
-            'on_response': [{'filter': MandayeFilter.addtoolbar,},]
+            'on_response': [
+                {
+                    'filter': MandayeFilter.addtoolbar,
+                    'content-types': ['text/html'],
+                    }
+                ]
             },
         {
             'path': r'/mandaye/toolbar',