diff --git a/main.c b/main.c
index a2e369a..42477f8 100644
--- a/main.c
+++ b/main.c
@@ -72,7 +72,7 @@ int main(void) {
     /* Send any available data to the NFC CDC */
     if (!ringbuffer_empty(uart_to_usb_buf)) {
       unsigned len = ringbuffer_peek(uart_to_usb_buf, &buf[0], sizeof buf);
-      if(usb_write_cdcacm(ACM_NFC, buf, len, 1)) {
+      if(usb_write_cdcacm(ACM_NFC, &buf[0], len, 1)) {
         ringbuffer_skip(uart_to_usb_buf, len);
       }
     }
diff --git a/ringbuffer.c b/ringbuffer.c
index 0dbb39b..e502cf6 100644
--- a/ringbuffer.c
+++ b/ringbuffer.c
@@ -29,7 +29,8 @@ unsigned ringbuffer_level(ringbuffer *buf) {
   return size - tail + head;
 }
 
-unsigned ringbuffer_add(ringbuffer *buf, uint8_t *dat, unsigned len) {
+unsigned ringbuffer_add(ringbuffer *buf, void *dat_, unsigned len) {
+  uint8_t *dat = dat_;
   unsigned rem = ringbuffer_free(buf);
   unsigned head = buf->head;
   unsigned written = 0;
@@ -55,7 +56,8 @@ unsigned ringbuffer_empty(ringbuffer *buf) {
   return buf->head == buf->tail;
 }
 
-unsigned ringbuffer_peek(ringbuffer *buf, uint8_t *dst, unsigned len) {
+unsigned ringbuffer_peek(ringbuffer *buf, void *dst_, unsigned len) {
+  uint8_t *dst = dst_;
   unsigned level = ringbuffer_level(buf);
   unsigned size = buf->size;
   unsigned tail = buf->tail;
@@ -78,7 +80,7 @@ void ringbuffer_skip(ringbuffer *buf, unsigned len) {
   buf->tail = (buf->tail + len) % (buf->size);
 }
 
-unsigned ringbuffer_get(ringbuffer *buf, uint8_t *dst, unsigned len) {
+unsigned ringbuffer_get(ringbuffer *buf, void *dst, unsigned len) {
   len = ringbuffer_peek(buf, dst, len);
   ringbuffer_skip(buf, len);
   return len;
diff --git a/ringbuffer.h b/ringbuffer.h
index 4cca110..3fe38fc 100644
--- a/ringbuffer.h
+++ b/ringbuffer.h
@@ -26,10 +26,10 @@ unsigned ringbuffer_level(ringbuffer *buf);
 
 unsigned ringbuffer_empty(ringbuffer *buf);
 
-unsigned ringbuffer_add(ringbuffer *buf, uint8_t *dat, unsigned len);
+unsigned ringbuffer_add(ringbuffer *buf, void *dat, unsigned len);
 
-unsigned ringbuffer_get(ringbuffer *buf, uint8_t *dst, unsigned len);
-unsigned ringbuffer_peek(ringbuffer *buf, uint8_t *dst, unsigned len);
+unsigned ringbuffer_get(ringbuffer *buf, void *dst, unsigned len);
+unsigned ringbuffer_peek(ringbuffer *buf, void *dst, unsigned len);
 void ringbuffer_skip(ringbuffer *buf, unsigned len);
 
 #ifdef __cplusplus
diff --git a/usb.c b/usb.c
index 7342a43..633fa5d 100644
--- a/usb.c
+++ b/usb.c
@@ -148,7 +148,7 @@ static void cdcacm_data_rx_cb(usbd_device *usbd_dev, uint8_t ep)
   }
 }
 
-int usb_write_cdcacm(uint8_t acm, uint8_t *data, size_t len, int tries) {
+int usb_write_cdcacm(uint8_t acm, void *data, size_t len, int tries) {
   int i = 0;
   while (usbd_ep_write_packet(g_usbd_dev, (1 + 2 * acm) | 0x80, data, len) == 0 && ++i < tries)
     ;
diff --git a/usb.h b/usb.h
index ac27354..f9437dc 100644
--- a/usb.h
+++ b/usb.h
@@ -6,7 +6,7 @@
 extern usbd_device *g_usbd_dev;
 
 void usb_setup(void);
-int usb_write_cdcacm(uint8_t acm, uint8_t *data, size_t len, int tries);
+int usb_write_cdcacm(uint8_t acm, void *data, size_t len, int tries);
 
 #define ACM_NFC 1
 #define ACM_COMM 0