diff --git a/resources/chapters/chapter-8.edn b/resources/chapters/chapter-8.edn
index 7661f17..900a9d7 100644
--- a/resources/chapters/chapter-8.edn
+++ b/resources/chapters/chapter-8.edn
@@ -28,7 +28,8 @@
                       [(not= ?p1 ?p2)]]
                      [(friends ?p1 ?p2)
                       [?m :movie/cast ?p1]
-                      [?m :movie/director ?p2]]
+                      [?m :movie/director ?p2]
+                      [(not= ?p1 ?p2)]]
                      [(friends ?p1 ?p2)
                       (friends ?p2 ?p1)]]}
     {:type :value