diff --git a/django/template/defaultfilters.py b/django/template/defaultfilters.py
index 76d723e0eb..e62e2e3eaf 100644
--- a/django/template/defaultfilters.py
+++ b/django/template/defaultfilters.py
@@ -25,6 +25,8 @@ def stringfilter(func):
         if args:
             args = list(args)
             args[0] = force_unicode(args[0])
+        if isinstance(args[0], SafeData) and getattr(func, 'is_safe', False):
+            return mark_safe(func(*args, **kwargs))
         return func(*args, **kwargs)
 
     # Include a reference to the real function (used to check original