diff --git a/src/class/cdc/cdc_host.c b/src/class/cdc/cdc_host.c
index a6dfb45ae2..b20da37237 100644
--- a/src/class/cdc/cdc_host.c
+++ b/src/class/cdc/cdc_host.c
@@ -80,6 +80,7 @@ static cdch_interface_t cdch_data[CFG_TUH_CDC];
 //--------------------------------------------------------------------+
 
 //------------- ACM prototypes -------------//
+static bool acm_open(uint8_t daddr, tusb_desc_interface_t const *itf_desc, uint16_t max_len);
 static void acm_process_config(tuh_xfer_t* xfer);
 
 static bool acm_set_line_coding(cdch_interface_t* p_cdc, cdc_line_coding_t const* line_coding, tuh_xfer_cb_t complete_cb, uintptr_t user_data);
@@ -605,8 +606,6 @@ bool cdch_xfer_cb(uint8_t daddr, uint8_t ep_addr, xfer_result_t event, uint32_t
 // Enumeration
 //--------------------------------------------------------------------+
 
-static bool acm_open(uint8_t daddr, tusb_desc_interface_t const *itf_desc, uint16_t max_len);
-
 static bool open_ep_stream_pair(cdch_interface_t* p_cdc, tusb_desc_endpoint_t const *desc_ep)
 {
   for(size_t i=0; i<2; i++)