diff --git a/theories/base_logic/lib/namespaces.v b/theories/base_logic/lib/namespaces.v
index d1f987623085f212d1b396cc27119b8a60452021..ccbe3d0634790c096cf5d388ca04a935c16e4561 100644
--- a/theories/base_logic/lib/namespaces.v
+++ b/theories/base_logic/lib/namespaces.v
@@ -100,3 +100,4 @@ Ltac solve_ndisj :=
   | H : _ ∪ _ ⊆ _ |- _ => apply union_subseteq in H as [??]
   end;
   solve [eauto with ndisj].
+Hint Extern 1000 => solve_ndisj : solve_ndisj.