diff --git a/src/HottBook/Chapter2.lagda.md b/src/HottBook/Chapter2.lagda.md
index 2d2833a..15d6f74 100644
--- a/src/HottBook/Chapter2.lagda.md
+++ b/src/HottBook/Chapter2.lagda.md
@@ -308,8 +308,12 @@ idToEquiv {A} {B} p = func , equiv
 
     homotopy : (func ∘ func-inv) ∼ id
     homotopy x = 
-      let wtf = transport id (sym p) (transport id p x) in
-      {!  !}
+      let
+        wtf x = transport id (sym p) (transport id p x)
+
+        wtf2 : (func ∘ func-inv) ≡ wtf
+        wtf2 = refl
+      in {!  !}
 
     equiv = record
       { g = func-inv