diff --git a/selfdrive/modeld/models/dmonitoring.cc b/selfdrive/modeld/models/dmonitoring.cc
index 6dc90718d1..15b28dd8d6 100644
--- a/selfdrive/modeld/models/dmonitoring.cc
+++ b/selfdrive/modeld/models/dmonitoring.cc
@@ -144,7 +144,7 @@ DMonitoringResult dmonitoring_eval_frame(DMonitoringModelState* s, void* stream_
   return ret;
 }
 
-void dmonitoring_publish(PubMaster &pm, uint32_t frame_id, const DMonitoringResult res) {
+void dmonitoring_publish(PubMaster &pm, uint32_t frame_id, const DMonitoringResult &res){
   // make msg
   capnp::MallocMessageBuilder msg;
   cereal::Event::Builder event = msg.initRoot<cereal::Event>();
diff --git a/selfdrive/modeld/models/dmonitoring.h b/selfdrive/modeld/models/dmonitoring.h
index c0a0cf4463..83d014f8db 100644
--- a/selfdrive/modeld/models/dmonitoring.h
+++ b/selfdrive/modeld/models/dmonitoring.h
@@ -37,7 +37,7 @@ typedef struct DMonitoringModelState {
 
 void dmonitoring_init(DMonitoringModelState* s);
 DMonitoringResult dmonitoring_eval_frame(DMonitoringModelState* s, void* stream_buf, int width, int height);
-void dmonitoring_publish(PubMaster &pm, uint32_t frame_id, const DMonitoringResult res);
+void dmonitoring_publish(PubMaster &pm, uint32_t frame_id, const DMonitoringResult &res);
 void dmonitoring_free(DMonitoringModelState* s);
 
 #ifdef __cplusplus