diff --git a/src/stm32/cdcacm.c b/src/stm32/cdcacm.c
index 5c61eb78..7107b930 100644
--- a/src/stm32/cdcacm.c
+++ b/src/stm32/cdcacm.c
@@ -83,14 +83,14 @@ static const struct usb_endpoint_descriptor gdb_data_endp[] = {{
 	.bDescriptorType = USB_DT_ENDPOINT,
 	.bEndpointAddress = 0x01,
 	.bmAttributes = USB_ENDPOINT_ATTR_BULK,
-	.wMaxPacketSize = 64,
+	.wMaxPacketSize = CDCACM_PACKET_SIZE,
 	.bInterval = 1,
 }, {
 	.bLength = USB_DT_ENDPOINT_SIZE,
 	.bDescriptorType = USB_DT_ENDPOINT,
 	.bEndpointAddress = 0x81,
 	.bmAttributes = USB_ENDPOINT_ATTR_BULK,
-	.wMaxPacketSize = 64,
+	.wMaxPacketSize = CDCACM_PACKET_SIZE,
 	.bInterval = 1,
 }};
 
@@ -187,14 +187,14 @@ static const struct usb_endpoint_descriptor uart_data_endp[] = {{
 	.bDescriptorType = USB_DT_ENDPOINT,
 	.bEndpointAddress = 0x03,
 	.bmAttributes = USB_ENDPOINT_ATTR_BULK,
-	.wMaxPacketSize = 64,
+	.wMaxPacketSize = CDCACM_PACKET_SIZE,
 	.bInterval = 1,
 }, {
 	.bLength = USB_DT_ENDPOINT_SIZE,
 	.bDescriptorType = USB_DT_ENDPOINT,
 	.bEndpointAddress = 0x83,
 	.bmAttributes = USB_ENDPOINT_ATTR_BULK,
-	.wMaxPacketSize = 64,
+	.wMaxPacketSize = CDCACM_PACKET_SIZE,
 	.bInterval = 1,
 }};
 
@@ -459,8 +459,8 @@ static void cdcacm_data_rx_cb(u8 ep)
 {
 	(void)ep;
 
-	char buf[64];
-	int len = usbd_ep_read_packet(0x03, buf, 64);
+	char buf[CDCACM_PACKET_SIZE];
+	int len = usbd_ep_read_packet(0x03, buf, CDCACM_PACKET_SIZE);
 	for(int i = 0; i < len; i++)
 		usart_send_blocking(USART1, buf[i]);
 }
@@ -471,14 +471,14 @@ static void cdcacm_set_config(u16 wValue)
 	configured = wValue;
 
 	/* GDB interface */
-	usbd_ep_setup(0x01, USB_ENDPOINT_ATTR_BULK, 64, NULL);
-	usbd_ep_setup(0x81, USB_ENDPOINT_ATTR_BULK, 64, NULL);
+	usbd_ep_setup(0x01, USB_ENDPOINT_ATTR_BULK, CDCACM_PACKET_SIZE, NULL);
+	usbd_ep_setup(0x81, USB_ENDPOINT_ATTR_BULK, CDCACM_PACKET_SIZE, NULL);
 	usbd_ep_setup(0x82, USB_ENDPOINT_ATTR_INTERRUPT, 16, NULL);
 
 #ifdef INCLUDE_UART_INTERFACE
 	/* Serial interface */
-	usbd_ep_setup(0x03, USB_ENDPOINT_ATTR_BULK, 64, cdcacm_data_rx_cb);
-	usbd_ep_setup(0x83, USB_ENDPOINT_ATTR_BULK, 64, NULL);
+	usbd_ep_setup(0x03, USB_ENDPOINT_ATTR_BULK, CDCACM_PACKET_SIZE, cdcacm_data_rx_cb);
+	usbd_ep_setup(0x83, USB_ENDPOINT_ATTR_BULK, CDCACM_PACKET_SIZE, NULL);
 	usbd_ep_setup(0x84, USB_ENDPOINT_ATTR_INTERRUPT, 16, NULL);
 #endif
 
diff --git a/src/stm32/gdb_if.c b/src/stm32/gdb_if.c
index 59e9c2b7..aa43293c 100644
--- a/src/stm32/gdb_if.c
+++ b/src/stm32/gdb_if.c
@@ -27,18 +27,16 @@
 
 #include "gdb_if.h"
 
-#define VIRTUAL_COM_PORT_DATA_SIZE 64
-
 static uint32_t count_out;
 static uint32_t count_in;
 static uint32_t out_ptr;
-static uint8_t buffer_out[VIRTUAL_COM_PORT_DATA_SIZE];
-static uint8_t buffer_in[VIRTUAL_COM_PORT_DATA_SIZE];
+static uint8_t buffer_out[CDCACM_PACKET_SIZE];
+static uint8_t buffer_in[CDCACM_PACKET_SIZE];
 
 void gdb_if_putchar(unsigned char c, int flush)
 {
 	buffer_in[count_in++] = c;
-	if(flush || (count_in == VIRTUAL_COM_PORT_DATA_SIZE)) {
+	if(flush || (count_in == CDCACM_PACKET_SIZE)) {
 		/* Refuse to send if USB isn't configured, and
 		 * don't bother if nobody's listening */
 		if((cdcacm_get_config() != 1) || !cdcacm_get_dtr()) {
@@ -59,7 +57,7 @@ unsigned char gdb_if_getchar(void)
 
 		while(cdcacm_get_config() != 1);
 		count_out = usbd_ep_read_packet(1, buffer_out, 
-					VIRTUAL_COM_PORT_DATA_SIZE);
+					CDCACM_PACKET_SIZE);
 		out_ptr = 0;
 	}
 
@@ -76,7 +74,7 @@ unsigned char gdb_if_getchar_to(int timeout)
 			return 0x04;
 
 		count_out = usbd_ep_read_packet(1, buffer_out, 
-					VIRTUAL_COM_PORT_DATA_SIZE);
+					CDCACM_PACKET_SIZE);
 		out_ptr = 0;
 	} while(timeout_counter && !(out_ptr < count_out));
 
diff --git a/src/stm32/platform.h b/src/stm32/platform.h
index a9a1ccae..85ade4f0 100644
--- a/src/stm32/platform.h
+++ b/src/stm32/platform.h
@@ -33,6 +33,7 @@
 
 #define INCLUDE_UART_INTERFACE
 #define INLINE_GPIO
+#define CDCACM_PACKET_SIZE 	64
 
 /* Important pin mappings for STM32 implementation:
  *