diff --git a/src/Toplevel.hs b/src/Toplevel.hs
index 981d5ce..16c56ca 100644
--- a/src/Toplevel.hs
+++ b/src/Toplevel.hs
@@ -85,7 +85,7 @@ detectLoop v g i =
      else case M.lookup i g of
        Nothing -> pure v -- this has already been removed, meaning this branch is safe
        Just is -> if is == S.empty
-                     then pure v -- leaf                               \/ Set not Traversable
+                     then pure (S.insert i v)
                      else S.unions <$> detectLoop (S.insert i v) g <~> S.toList is
 
 createGraph :: [TL] -> RefGraph
diff --git a/test.hm b/test.hm
index f44dd8a..adf26ac 100644
--- a/test.hm
+++ b/test.hm
@@ -54,4 +54,8 @@ isEven : Nat → Bool
 
 type bot
 
-absurd : bot -> A := rec[bot]
+absurd : bot -> A
+  := rec[bot]
+
+id : A -> A
+ := λx. x