diff --git a/internal/rosa/package/go/820480.patch b/internal/rosa/package/go/820480.patch
new file mode 100644
index 00000000..05459a80
--- /dev/null
+++ b/internal/rosa/package/go/820480.patch
@@ -0,0 +1,24 @@
+From fa10bbcce5635dd533ba933252e9dabd8a7f5e2a Mon Sep 17 00:00:00 2001
+From: David Chase <drchase@google.com>
+Date: Mon, 24 Aug 2026 15:20:40 -0400
+Subject: [PATCH] simd/archsimd: added PMULL gate on carryless multiply test
+
+Fixes #80991.
+
+Change-Id: I637de72acbb338c4c3b0a47f4a5520c33fe81fd2
+---
+
+diff --git a/src/simd/archsimd/internal/simd_test/simd_arm64_test.go b/src/simd/archsimd/internal/simd_test/simd_arm64_test.go
+index f009488..7836fc8 100644
+--- a/src/simd/archsimd/internal/simd_test/simd_arm64_test.go
++++ b/src/simd/archsimd/internal/simd_test/simd_arm64_test.go
+@@ -22,6 +22,9 @@
+ }
+ 
+ func TestClMul(t *testing.T) {
++	if !archsimd.ARM64.PMULL() {
++		t.Skip("no carryless multiply")
++	}
+ 	var x = archsimd.LoadUint64x2([]uint64{1, 5})
+ 	var y = archsimd.LoadUint64x2([]uint64{3, 9})
+ 
diff --git a/internal/rosa/package/go.az b/internal/rosa/package/go/package.az
similarity index 97%
rename from internal/rosa/package/go.az
rename to internal/rosa/package/go/package.az
index 096bb2fb..d06720b5 100644
--- a/internal/rosa/package/go.az
+++ b/internal/rosa/package/go/package.az
@@ -9,6 +9,7 @@ package go {
 		checksum = "Ookl2vP6KMfJuxaxX6nXZ1gnL43wZPl5GjpVsrI7IJiB4b3xr1PbnbYIOJ8v5jzG";
 		compress = gzip;
 	};
+	patches = [ "820480.patch" ];
 
 	env = [
 		"CC=cc",