diff --git a/mercurial/templater.py b/mercurial/templater.py
--- a/mercurial/templater.py
+++ b/mercurial/templater.py
@@ -1371,6 +1371,7 @@
 
     def render(self, mapping):
         """Render the default unnamed template and return result as string"""
+        mapping = pycompat.strkwargs(mapping)
         return stringify(self('', **mapping))
 
     def __call__(self, t, **mapping):