diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 7ecf688f18..a0644e39ec 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -2619,6 +2619,8 @@ func intrinsicInit() {
 	// aliases internal to runtime/internal/atomic
 	i.std[intrinsicKey{"runtime/internal/atomic", "Loadint64"}] =
 		i.std[intrinsicKey{"runtime/internal/atomic", "Load64"}]
+	i.std[intrinsicKey{"runtime/internal/atomic", "Xaddint64"}] =
+		i.std[intrinsicKey{"runtime/internal/atomic", "Xadd64"}]
 
 	// intrinsics which vary depending on the size of int/ptr.
 	i.intSized = map[sizedIntrinsicKey]intrinsicBuilder{