diff --git a/qutebrowser/browser/webengine/webengineelem.py b/qutebrowser/browser/webengine/webengineelem.py
index cb1e973b0..39489eb9a 100644
--- a/qutebrowser/browser/webengine/webengineelem.py
+++ b/qutebrowser/browser/webengine/webengineelem.py
@@ -47,7 +47,10 @@ class WebEngineElement(webelem.AbstractWebElement):
         return attrs[key]
 
     def __setitem__(self, key, val):
-        log.stub()
+        self._js_dict['attributes'][key] = val
+        js_code = javascript.assemble('webelem', 'set_attribute', self._id,
+            key, val)
+        self._tab.run_js_async(js_code)
 
     def __delitem__(self, key):
         log.stub()
diff --git a/qutebrowser/javascript/webelem.js b/qutebrowser/javascript/webelem.js
index 3e38c8adb..6a5e1425f 100644
--- a/qutebrowser/javascript/webelem.js
+++ b/qutebrowser/javascript/webelem.js
@@ -155,5 +155,9 @@ window._qutebrowser.webelem = (function() {
         return serialize_elem(elem);
     };
 
+    funcs.set_attribute = function(id, name, value) {
+        elements[id].setAttribute(name, value);
+    };
+
     return funcs;
 })();