diff --git a/topi/include/topi/generic/default.h b/topi/include/topi/generic/default.h
index c44bc69190f4..403b943a16e6 100644
--- a/topi/include/topi/generic/default.h
+++ b/topi/include/topi/generic/default.h
@@ -43,7 +43,7 @@ namespace generic {
  *
  * \return A schedule for the given ops.
  */
-inline Schedule default_schedule(const Target& target, Array<Tensor> outs) {
+inline Schedule default_schedule(const Target& target, const Array<Tensor>& outs) {
   Array<Operation> out_ops;
   for (auto t : outs) {
     out_ops.push_back(t->op);
@@ -61,7 +61,7 @@ inline Schedule default_schedule(const Target& target, Array<Tensor> outs) {
  *
  * \return A schedule for the given ops.
  */
-inline Schedule default_schedule_auto_inline(const Target& target, Array<Tensor> outs) {
+inline Schedule default_schedule_auto_inline(const Target& target, const Array<Tensor>& outs) {
   Array<Operation> out_ops;
   for (auto t : outs) {
     out_ops.push_back(t->op);
diff --git a/topi/include/topi/generic/extern.h b/topi/include/topi/generic/extern.h
index 6e5507b4e77b..3954ac69ada8 100644
--- a/topi/include/topi/generic/extern.h
+++ b/topi/include/topi/generic/extern.h
@@ -44,7 +44,7 @@ namespace generic {
  *
  * \return A schedule for the op.
  */
-inline Schedule schedule_extern(const Target& target, Array<Tensor> outs) {
+inline Schedule schedule_extern(const Target& target, const Array<Tensor>& outs) {
   Array<Operation> out_ops;
   for (auto t : outs) {
     out_ops.push_back(t->op);