diff --git a/tests/test_resources.py b/tests/test_resources.py
index b913beb..ee80cc5 100644
--- a/tests/test_resources.py
+++ b/tests/test_resources.py
@@ -262,8 +262,9 @@ class TestJsFuncall(tb.WidgetTest):
     expected = None
 
     def test_display(self):
-        r = self.widget(**self.attrs).display(**self.params)
-        assert r == """<script type="text/javascript">foo("a", "b")</script>""", r
+        for t in self._get_all_possible_engines():
+            r = self.widget(**self.attrs).display(template='%s:%s' % (t, twr._JSFuncCall.template))
+            assert r == """<script type="text/javascript">foo("a", "b")</script>""", r
 
 from pkg_resources import Requirement
 class TestResourcesApp:
diff --git a/tw2/core/resources.py b/tw2/core/resources.py
index b3c7f9e..becf832 100644
--- a/tw2/core/resources.py
+++ b/tw2/core/resources.py
@@ -16,6 +16,8 @@
 import middleware as md
 from js import encoder, js_symbol
 
+from markupsafe import Markup
+
 log = logging.getLogger(__name__)
 
 
@@ -275,7 +277,7 @@ def prepare(self):
             elif self.args:
                 args = ', '.join(encoder.encode(a) for a in self.args)
 
-            self.src = '%s(%s)' % (self.function, args)
+            self.src = Markup('%s(%s)' % (self.function, args))
         super(_JSFuncCall, self).prepare()
 
     def __hash__(self):