diff --git a/sys/include/usb/usbus/cdc/acm.h b/sys/include/usb/usbus/cdc/acm.h
index 8bd2f09c48..231d018446 100644
--- a/sys/include/usb/usbus/cdc/acm.h
+++ b/sys/include/usb/usbus/cdc/acm.h
@@ -46,8 +46,8 @@ extern "C" {
  * @brief Buffer size for STDIN and STDOUT data to and from USB when using
  *        the USBUS_CDC_ACM_STDIO module
  */
-#ifndef USBUS_CDC_ACM_STDIO_BUF_SIZE
-#define USBUS_CDC_ACM_STDIO_BUF_SIZE (128)
+#ifndef CONFIG_USBUS_CDC_ACM_STDIO_BUF_SIZE
+#define CONFIG_USBUS_CDC_ACM_STDIO_BUF_SIZE (128)
 #endif
 
 /**
diff --git a/sys/usb/usbus/cdc/acm/cdc_acm_stdio.c b/sys/usb/usbus/cdc/acm/cdc_acm_stdio.c
index a14dc1a073..9b133c15e8 100644
--- a/sys/usb/usbus/cdc/acm/cdc_acm_stdio.c
+++ b/sys/usb/usbus/cdc/acm/cdc_acm_stdio.c
@@ -38,8 +38,8 @@
 #endif
 
 static usbus_cdcacm_device_t cdcacm;
-static uint8_t _cdc_tx_buf_mem[USBUS_CDC_ACM_STDIO_BUF_SIZE];
-static uint8_t _cdc_rx_buf_mem[USBUS_CDC_ACM_STDIO_BUF_SIZE];
+static uint8_t _cdc_tx_buf_mem[CONFIG_USBUS_CDC_ACM_STDIO_BUF_SIZE];
+static uint8_t _cdc_rx_buf_mem[CONFIG_USBUS_CDC_ACM_STDIO_BUF_SIZE];
 static isrpipe_t _cdc_stdio_isrpipe = ISRPIPE_INIT(_cdc_rx_buf_mem);
 
 void stdio_init(void)