diff --git a/stdpp/base.v b/stdpp/base.v
index 210ebad0e0dfe45467a2b2ace971a23f69d8d5c8..e6fb1b49051babfcc46f394a4ec1663073d76488 100644
--- a/stdpp/base.v
+++ b/stdpp/base.v
@@ -476,6 +476,10 @@ Proof. repeat intro; edestruct (inj2 f); eauto. Qed.
 Global Instance inj2_inj_2 `{Inj2 A B C R1 R2 R3 f} x : Inj R2 R3 (f x).
 Proof. repeat intro; edestruct (inj2 f); eauto. Qed.
 
+(** Smart constructors for [Inj] and [Surj] based on [Cancel]. These are not
+instances because they will blow-up the search space, i.e., in every node of
+the search tree for [Inj] or [Surj] of composed functions these instances could
+be applied. *)
 Lemma cancel_inj `{Cancel A B R1 f g, !Equivalence R1, !Proper (R2 ==> R1) f} :
   Inj R1 R2 g.
 Proof.