diff --git a/selfdrive/boardd/panda.cc b/selfdrive/boardd/panda.cc
index 9c59bba6fc..75458974fc 100644
--- a/selfdrive/boardd/panda.cc
+++ b/selfdrive/boardd/panda.cc
@@ -352,7 +352,7 @@ void Panda::set_data_speed_kbps(uint16_t bus, uint16_t speed) {
   usb_write(0xf9, bus, (speed * 10));
 }
 
-uint8_t Panda::len_to_dlc(uint8_t len) {
+static uint8_t len_to_dlc(uint8_t len) {
   if (len <= 8) {
     return len;
   }
diff --git a/selfdrive/boardd/panda.h b/selfdrive/boardd/panda.h
index 9ac75c968a..79124a59b1 100644
--- a/selfdrive/boardd/panda.h
+++ b/selfdrive/boardd/panda.h
@@ -112,7 +112,6 @@ class Panda {
   void send_heartbeat();
   void set_can_speed_kbps(uint16_t bus, uint16_t speed);
   void set_data_speed_kbps(uint16_t bus, uint16_t speed);
-  uint8_t len_to_dlc(uint8_t len);
   void can_send(capnp::List<cereal::CanData>::Reader can_data_list);
   bool can_receive(std::vector<can_frame>& out_vec);