diff --git a/theories/proofmode/class_instances.v b/theories/proofmode/class_instances.v
index f818a7b9cac012af05d4c4d021c890126853184c..8a1bc66264b68acc943e6b95cacce4c7960ed63e 100644
--- a/theories/proofmode/class_instances.v
+++ b/theories/proofmode/class_instances.v
@@ -1198,6 +1198,31 @@ Proof.
   by rewrite (into_except_0 P) -except_0_sep wand_elim_r.
 Qed.
 
+(* AddModal *)
+(* High priority to add a â–· rather than a â—‡ when P is timeless. *)
+Global Instance add_modal_later_except_0 P Q :
+  Timeless P → AddModal (▷ P) P (◇ Q) | 0.
+Proof.
+  intros. rewrite /AddModal (except_0_intro (_ -∗ _)%I) (timeless P).
+  by rewrite -except_0_sep wand_elim_r except_0_idemp.
+Qed.
+Global Instance add_modal_later P Q :
+  Timeless P → AddModal (▷ P) P (▷ Q) | 0.
+Proof.
+  intros. rewrite /AddModal (except_0_intro (_ -∗ _)%I) (timeless P).
+  by rewrite -except_0_sep wand_elim_r except_0_later.
+Qed.
+Global Instance add_modal_except_0 P Q : AddModal (â—‡ P) P (â—‡ Q) | 1.
+Proof.
+  intros. rewrite /AddModal (except_0_intro (_ -∗ _)%I).
+  by rewrite -except_0_sep wand_elim_r except_0_idemp.
+Qed.
+Global Instance add_modal_except_0_later P Q : AddModal (â—‡ P) P (â–· Q) | 1.
+Proof.
+  intros. rewrite /AddModal (except_0_intro (_ -∗ _)%I).
+  by rewrite -except_0_sep wand_elim_r except_0_later.
+Qed.
+
 (* Frame *)
 Class MakeLater (P lP : PROP) := make_later : ▷ P ⊣⊢ lP.
 Arguments MakeLater _%I _%I.