diff --git a/composer/schema/field.py b/composer/schema/field.py
index 0426396..bdef21a 100644
--- a/composer/schema/field.py
+++ b/composer/schema/field.py
@@ -345,7 +345,7 @@ class ListFieldInstance(FieldInstance):
             return u''
         if isinstance(value, basestring):
             return value
-        return u' | '.join(self.valueFieldInstance.display(v) for v in value)
+        return u' | '.join(unicode(self.valueFieldInstance.display(v)) for v in value)
 
     def unmarshall(self, value):
         if isinstance(value, basestring):