diff --git a/include/usbd_gs_can.h b/include/usbd_gs_can.h
index a514073..217537f 100644
--- a/include/usbd_gs_can.h
+++ b/include/usbd_gs_can.h
@@ -100,4 +100,3 @@ bool USBD_GS_CAN_CustomInterfaceRequest(USBD_HandleTypeDef *pdev, USBD_SetupReqT
 
 bool USBD_GS_CAN_DfuDetachRequested(USBD_HandleTypeDef *pdev);
 uint8_t USBD_GS_CAN_SendFrame(USBD_HandleTypeDef *pdev, struct gs_host_frame *frame);
-uint8_t USBD_GS_CAN_Transmit(USBD_HandleTypeDef *pdev, uint8_t *buf, uint16_t len);
diff --git a/src/usbd_gs_can.c b/src/usbd_gs_can.c
index 4ca7170..1c95144 100644
--- a/src/usbd_gs_can.c
+++ b/src/usbd_gs_can.c
@@ -644,7 +644,7 @@ bool USBD_GS_CAN_TxReady(USBD_HandleTypeDef *pdev)
 	return result;
 }
 
-uint8_t USBD_GS_CAN_Transmit(USBD_HandleTypeDef *pdev, uint8_t *buf, uint16_t len)
+static uint8_t USBD_GS_CAN_Transmit(USBD_HandleTypeDef *pdev, uint8_t *buf, uint16_t len)
 {
 	USBD_GS_CAN_HandleTypeDef *hcan = (USBD_GS_CAN_HandleTypeDef*)pdev->pClassData;
 	if (hcan->TxState == 0 && (false == is_usb_suspend_cb)) {