diff --git a/theories/lang/memcpy.v b/theories/lang/memcpy.v
index 4df0f9c53206a57173a62d7a37c74b1ba73a5b96..dc60165b24657a89a3f83f96ee438b6caaba645a 100644
--- a/theories/lang/memcpy.v
+++ b/theories/lang/memcpy.v
@@ -32,7 +32,6 @@ Proof.
   - destruct vl1 as [|v1 vl1], vl2 as [|v2 vl2], n as [|n|]; try (discriminate || lia).
     revert Hvl1 Hvl2. intros [= Hvl1] [= Hvl2]; rewrite !own_loc_na_vec_cons. subst n.
     iDestruct "Hl1" as "[Hv1 Hl1]". iDestruct "Hl2" as "[Hv2 Hl2]".
-    Local Opaque Zminus.
     wp_read; wp_write. do 3 wp_op. iApply ("IH" with "[%] [%] Hl1 Hl2"); [lia..|].
     iIntros "!> [Hl1 Hl2]"; iApply "HΦ"; by iFrame.
 Qed.