diff --git a/tastypie_swagger/mapping.py b/tastypie_swagger/mapping.py
index d85748e..66ddd26 100644
--- a/tastypie_swagger/mapping.py
+++ b/tastypie_swagger/mapping.py
@@ -201,7 +201,7 @@ def build_parameters_from_filters(self, prefix="", method='GET'):
                         if field == ALL:
                             has_related_resource = False
                         else:
-                            has_related_resource = hasattr(self.resource.fields[name], 'get_related_resource')
+                            has_related_resource = hasattr(self.resource.fields.get(name), 'get_related_resource')
 
                         if not has_related_resource:
                             #This code has been mostly sucked from the tastypie lib