diff --git a/stdpp/base.v b/stdpp/base.v
index 4aaf037604acf23d13fe0806fd5d61df7e9e5859..29f1d074ff4fb6ac1e99bfad531207988eee56fd 100644
--- a/stdpp/base.v
+++ b/stdpp/base.v
@@ -56,6 +56,7 @@ Add Search Blacklist "_unseal".
 Record seal {A} (f : A) := { unseal : A; seal_eq : unseal = f }.
 Global Arguments unseal {_ _} _ : assert.
 Global Arguments seal_eq {_ _} _ : assert.
+Global Typeclasses Opaque unseal.
 
 (** * Solving type class instances *)
 (** The tactic [tc_solve] is used to solve type class goals by invoking type