diff --git a/drivers/include/usbdev_mock.h b/drivers/include/usbdev_mock.h
index 324dea8c83..d502a02a4d 100644
--- a/drivers/include/usbdev_mock.h
+++ b/drivers/include/usbdev_mock.h
@@ -40,10 +40,11 @@ typedef enum {
  * @brief usbdev mock device endpoint
  */
 typedef struct {
-    usbdev_ep_t ep;                 /**< Generic endpoint struct        */
-    usbdev_mock_ep_state_t state;   /**< Endpoint state                 */
-    size_t available;               /**< Bytes available in the buffer  */
-    uint8_t *buf_start;             /**< Start location of the buffer   */
+    usbdev_ep_t ep;                 /**< Generic endpoint struct                    */
+    usbdev_mock_ep_state_t state;   /**< Endpoint state                             */
+    size_t available;               /**< Bytes available in the buffer              */
+    uint8_t *target_buf;            /**< Buffer as passed by @ref usbdev_ep_xmit    */
+    uint8_t *buf;                   /**< Internal mock buffer pointer */
 } usbdev_mock_ep_t;
 
 /**
diff --git a/drivers/usbdev_mock/usbdev_mock.c b/drivers/usbdev_mock/usbdev_mock.c
index a3c9a9d3bf..944cef9381 100644
--- a/drivers/usbdev_mock/usbdev_mock.c
+++ b/drivers/usbdev_mock/usbdev_mock.c
@@ -75,16 +75,15 @@ usbdev_ep_t *_new_ep(usbdev_t *dev, usb_ep_type_t type, usb_ep_dir_t dir,
 
             res = &testdev->out[0];
             res->ep.num = 0;
-            res->ep.buf = _out_buf;
+            res->buf = _out_buf;
         }
         else {
             res = &testdev->in[0];
             res->ep.num = 0;
-            res->ep.buf = _in_buf;
+            res->buf = _in_buf;
         }
     }
     if (res) {
-        res->buf_start = res->ep.buf;
         res->state = EP_STATE_READY;
         res->available = 0;
         res->ep.len = buf_len;
@@ -190,26 +189,30 @@ void _ep_esr(usbdev_ep_t *ep)
           ep->num, ep->dir == USB_EP_DIR_OUT ? "out" : "in");
     usbdev_mock_ep_t *mock_ep = (usbdev_mock_ep_t *)ep;
 
+    if (mock_ep->ep.dir == USB_EP_DIR_OUT) {
+        memcpy(mock_ep->target_buf, mock_ep->buf, mock_ep->available);
+    }
     if (mock_ep->state == EP_STATE_DATA_AVAILABLE) {
         dev->ep_esr_cb(dev, mock_ep);
         mock_ep->state = EP_STATE_READY;
     }
 }
 
-int _ready(usbdev_ep_t *ep, size_t len)
+int _xmit(usbdev_ep_t *ep, uint8_t *buf, size_t len)
 {
     DEBUG("[mock]: Readying EP %u, dir %s, len %u\n",
           ep->num, ep->dir == USB_EP_DIR_OUT ? "out" : "in", (unsigned)len);
     if (ep->num == 0) {
         usbdev_mock_t *usbdev_mock = _ep2dev(ep);
         usbdev_mock_ep_t *mock_ep = (usbdev_mock_ep_t *)ep;
-
-        mock_ep->available = len;
-        mock_ep->ep.buf += len;
+        mock_ep->target_buf = buf;
+        if (ep->dir == USB_EP_DIR_IN) {
+            memcpy(mock_ep->buf + mock_ep->available, mock_ep->target_buf, len);
+            mock_ep->available = len;
+        }
         mock_ep->state = EP_STATE_DATA_AVAILABLE;
 
         usbdev_mock->ready_cb(usbdev_mock, (usbdev_mock_ep_t *)ep, len);
-
     }
     return 0;
 }
@@ -224,5 +227,5 @@ static const usbdev_driver_t testdriver = {
     .ep_get = _ep_get,
     .ep_set = _ep_set,
     .ep_esr = _ep_esr,
-    .ready = _ready,
+    .xmit = _xmit,
 };
diff --git a/tests/usbus/main.c b/tests/usbus/main.c
index a2ba8b4f8f..3ca6bf32dc 100644
--- a/tests/usbus/main.c
+++ b/tests/usbus/main.c
@@ -146,7 +146,7 @@ static void _test_sequence(usbdev_mock_t *dev)
         case TESTPHASE_RESET:
             next_phase = TESTPHASE_REQ_DEV_INIT;
             DEBUG("[test]: Requesting device descriptor\n");
-            _build_conf_req(dev->out[0].ep.buf, 8); /* initial config request */
+            _build_conf_req(dev->out[0].buf, 8); /* initial config request */
             dev->req_len = 8;
             dev->out[0].state = EP_STATE_DATA_AVAILABLE;
             dev->out[0].available = 8;
@@ -157,7 +157,7 @@ static void _test_sequence(usbdev_mock_t *dev)
             DEBUG("[test]: validating device descriptor\n");
             TEST_ASSERT_EQUAL_INT(dev->in[0].available, 8);
             _validate_device_desc_init(
-                (usb_descriptor_device_t *)dev->in[0].buf_start);
+                (usb_descriptor_device_t *)dev->in[0].buf);
             /* Reset device */
             DEBUG("[test]: Signalling second USB reset condition\n");
             dev->usbdev.cb(&dev->usbdev, USBDEV_EVENT_RESET);
@@ -166,7 +166,7 @@ static void _test_sequence(usbdev_mock_t *dev)
         case TESTPHASE_RESET2:
             next_phase = TESTPHASE_SET_ADDRESS;
             DEBUG("[test]: Set USB address\n");
-            _build_set_addr(dev->out[0].ep.buf);
+            _build_set_addr(dev->out[0].buf);
             dev->req_len = 0;
             dev->out[0].state = EP_STATE_DATA_AVAILABLE;
             dev->out[0].available = 8;
@@ -175,7 +175,7 @@ static void _test_sequence(usbdev_mock_t *dev)
         case TESTPHASE_SET_ADDRESS:
             next_phase = TESTPHASE_REQ_DEV_FULL;
             DEBUG("[test]: Requesting full device descriptor\n");
-            _build_conf_req(dev->out[0].ep.buf,
+            _build_conf_req(dev->out[0].buf,
                             sizeof(usb_descriptor_device_t));
             dev->req_len = sizeof(usb_descriptor_device_t);
             dev->out[0].state = EP_STATE_DATA_AVAILABLE;
@@ -187,7 +187,7 @@ static void _test_sequence(usbdev_mock_t *dev)
                                   sizeof(usb_descriptor_device_t));
             DEBUG("[test]: Validating full descriptor\n");
             _validate_device_desc_init(
-                (usb_descriptor_device_t *)dev->in[0].buf_start);
+                (usb_descriptor_device_t *)dev->in[0].buf);
 
             next_phase = TESTPHASE_FINAL;
             dev->usbdev.cb(&dev->usbdev, USBDEV_EVENT_ESR);
@@ -261,8 +261,6 @@ static void _handle_data(usbdev_mock_t *dev, usbdev_mock_ep_t *ep, size_t len)
         if (ep->available == dev->req_len) {
             DEBUG("[data]: Full data received from stack\n");
             req_phase = TEST_REQ_PHASE_OUTACK;
-            /* Reset buffer ptr to the start */
-            ep->ep.buf = ep->buf_start;
         }
         else {
             DEBUG("[data]: Expecting more data from stack: %u/%u\n",