diff --git a/django/template/defaultfilters.py b/django/template/defaultfilters.py
index b172be6239..298347429f 100644
--- a/django/template/defaultfilters.py
+++ b/django/template/defaultfilters.py
@@ -37,12 +37,11 @@ def stringfilter(func):
     passed as the first positional argument will be converted to a string.
     """
     def _dec(*args, **kwargs):
-        if args:
-            args = list(args)
-            args[0] = str(args[0])
-            if (isinstance(args[0], SafeData) and
-                    getattr(_dec._decorated_function, 'is_safe', False)):
-                return mark_safe(func(*args, **kwargs))
+        args = list(args)
+        args[0] = str(args[0])
+        if (isinstance(args[0], SafeData) and
+                getattr(_dec._decorated_function, 'is_safe', False)):
+            return mark_safe(func(*args, **kwargs))
         return func(*args, **kwargs)
 
     # Include a reference to the real function (used to check original