diff --git a/theories/streams.v b/theories/streams.v
index 2880a9a9c185c9ab2efcdfd672d19816938766cb..92304f4045604f8cd6fbea8c299d570e82a1083a 100644
--- a/theories/streams.v
+++ b/theories/streams.v
@@ -41,7 +41,7 @@ Proof. by constructor. Qed.
 Global Instance equal_equivalence : Equivalence (≡@{stream A}).
 Proof.
   split.
-  - now cofix FIX; intros [??]; constructor.
+  - now cofix FIX; intros ?; constructor.
   - now cofix FIX; intros ?? [??]; constructor.
   - cofix FIX; intros ??? [??] [??]; constructor; etrans; eauto.
 Qed.