diff --git a/src/Cat/Category/Monad.agda b/src/Cat/Category/Monad.agda
index 701c986..674fd95 100644
--- a/src/Cat/Category/Monad.agda
+++ b/src/Cat/Category/Monad.agda
@@ -28,6 +28,8 @@ module Monoidal {ℓa ℓb : Level} (ℂ : Category ℓa ℓb) where
       pureNT : NaturalTransformation F.identity R
       joinNT : NaturalTransformation F[ R ∘ R ] R
 
+    -- Note that `pureT` and `joinT` differs from their definition in the
+    -- kleisli formulation only by having an explicit parameter.
     pureT : Transformation F.identity R
     pureT = proj₁ pureNT
     pureN : Natural F.identity R pureT