diff --git a/nested_admin/nested.py b/nested_admin/nested.py
index a83b051..ccefd27 100644
--- a/nested_admin/nested.py
+++ b/nested_admin/nested.py
@@ -368,6 +368,14 @@ def _create_formsets(self, request, obj, change):
                         is_empty_form = True
                     InlineFormSet = inline.get_formset(request, form_obj)
 
+                    # Check if we're dealing with a polymorphic instance, and if
+                    # so, skip inlines for other child models
+                    if hasattr(form_obj, "get_real_instance"):
+                        if hasattr(InlineFormSet, "fk"):
+                            rel_model = InlineFormSet.fk.remote_field.model
+                            if not isinstance(form_obj, rel_model):
+                                continue
+
                     prefix = "{}-{}".format(
                         form_prefix, InlineFormSet.get_default_prefix()
                     )
@@ -375,13 +383,7 @@ def _create_formsets(self, request, obj, change):
                     if prefixes[prefix] != 1:
                         prefix = "{}-{}".format(prefix, prefixes[prefix])
 
-                    # Check if we're dealing with a polymorphic instance, and if
-                    # so, skip inlines for other child models
                     if hasattr(form_obj, "get_real_instance"):
-                        if hasattr(InlineFormSet, "fk"):
-                            rel_model = InlineFormSet.fk.remote_field.model
-                            if not isinstance(form_obj, rel_model):
-                                continue
                         if not isinstance(form_obj, inline.parent_model):
                             continue