diff --git a/protocol/chibios/usb_main.c b/protocol/chibios/usb_main.c
index 18104ac8..9d5b912c 100644
--- a/protocol/chibios/usb_main.c
+++ b/protocol/chibios/usb_main.c
@@ -63,11 +63,15 @@ extern bool keyboard_nkro;
 #endif /* NKRO_ENABLE */
 
 report_keyboard_t keyboard_report_sent = {{0}};
+report_keyboard_t *keyboard_report_not_yet_sent = NULL;
 #ifdef MOUSE_ENABLE
 report_mouse_t mouse_report_blank = {0};
+report_mouse_t *mouse_report_not_yet_sent = NULL;
 #endif /* MOUSE_ENABLE */
 #ifdef EXTRAKEY_ENABLE
 uint8_t extra_report_blank[3] = {0};
+report_extra_t extra_report_not_yet_sent;
+bool extra_report_waiting = FALSE;
 #endif /* EXTRAKEY_ENABLE */
 
 #ifdef CONSOLE_ENABLE
@@ -1066,17 +1070,23 @@ void send_remote_wakeup(USBDriver *usbp) {
 
 /* keyboard IN callback hander (a kbd report has made it IN) */
 void kbd_in_cb(USBDriver *usbp, usbep_t ep) {
-  /* STUB */
-  (void)usbp;
-  (void)ep;
+  if (keyboard_report_not_yet_sent != NULL) {
+    osalSysLockFromISR();
+    usbStartTransmitI(usbp, ep, (uint8_t *)keyboard_report_not_yet_sent, KBD_EPSIZE);
+    keyboard_report_not_yet_sent = NULL;
+    osalSysUnlockFromISR();
+  }
 }
 
 #ifdef NKRO_ENABLE
 /* nkro IN callback hander (a nkro report has made it IN) */
 void nkro_in_cb(USBDriver *usbp, usbep_t ep) {
-  /* STUB */
-  (void)usbp;
-  (void)ep;
+  if (keyboard_report_not_yet_sent != NULL) {
+    osalSysLockFromISR();
+    usbStartTransmitI(usbp, ep, (uint8_t *)keyboard_report_not_yet_sent, sizeof(report_keyboard_t));
+    keyboard_report_not_yet_sent = NULL;
+    osalSysUnlockFromISR();
+  }
 }
 #endif /* NKRO_ENABLE */
 
@@ -1132,41 +1142,30 @@ void send_keyboard(report_keyboard_t *report) {
     osalSysUnlock();
     return;
   }
-  osalSysUnlock();
 
 #ifdef NKRO_ENABLE
   if(keyboard_nkro) {  /* NKRO protocol */
     /* need to wait until the previous packet has made it through */
-    /* can rewrite this using the synchronous API, then would wait
-     * until *after* the packet has been transmitted. I think
-     * this is more efficient */
-    /* busy wait, should be short and not very common */
-    osalSysLock();
+    /* save the pointer to the current report to send it later */
     if(usbGetTransmitStatusI(&USB_DRIVER, NKRO_ENDPOINT)) {
-      /* Need to either suspend, or loop and call unlock/lock during
-       * every iteration - otherwise the system will remain locked,
-       * no interrupts served, so USB not going through as well.
-       * Note: for suspend, need USB_USE_WAIT == TRUE in halconf.h */
-      osalThreadSuspendS(&(&USB_DRIVER)->epc[NKRO_ENDPOINT]->in_state->thread);
+      keyboard_report_not_yet_sent = report;
+      osalSysUnlock();
+      return;
     }
     usbStartTransmitI(&USB_DRIVER, NKRO_ENDPOINT, (uint8_t *)report, sizeof(report_keyboard_t));
-    osalSysUnlock();
   } else
 #endif /* NKRO_ENABLE */
   { /* boot protocol */
     /* need to wait until the previous packet has made it through */
-    /* busy wait, should be short and not very common */
-    osalSysLock();
+    /* save the pointer to the current report to send it later */
     if(usbGetTransmitStatusI(&USB_DRIVER, KBD_ENDPOINT)) {
-      /* Need to either suspend, or loop and call unlock/lock during
-       * every iteration - otherwise the system will remain locked,
-       * no interrupts served, so USB not going through as well.
-       * Note: for suspend, need USB_USE_WAIT == TRUE in halconf.h */
-      osalThreadSuspendS(&(&USB_DRIVER)->epc[KBD_ENDPOINT]->in_state->thread);
+      keyboard_report_not_yet_sent = report;
+      osalSysUnlock();
+      return;
     }
     usbStartTransmitI(&USB_DRIVER, KBD_ENDPOINT, (uint8_t *)report, KBD_EPSIZE);
-    osalSysUnlock();
   }
+  osalSysUnlock();
   keyboard_report_sent = *report;
 }
 
@@ -1179,8 +1178,12 @@ void send_keyboard(report_keyboard_t *report) {
 
 /* mouse IN callback hander (a mouse report has made it IN) */
 void mouse_in_cb(USBDriver *usbp, usbep_t ep) {
-  (void)usbp;
-  (void)ep;
+  if (mouse_report_not_yet_sent != NULL) {
+    osalSysLockFromISR();
+    usbStartTransmitI(usbp, ep, (uint8_t *)mouse_report_not_yet_sent, sizeof(report_mouse_t));
+    mouse_report_not_yet_sent = NULL;
+    osalSysUnlockFromISR();
+  }
 }
 
 void send_mouse(report_mouse_t *report) {
@@ -1189,14 +1192,17 @@ void send_mouse(report_mouse_t *report) {
     osalSysUnlock();
     return;
   }
-  osalSysUnlock();
 
   /* TODO: LUFA manually waits for the endpoint to become ready
    * for about 10ms for mouse, kbd, system; 1ms for nkro
    * is this really needed?
    */
 
-  osalSysLock();
+  if (usbGetTransmitStatusI(&USB_DRIVER, MOUSE_ENDPOINT)) {
+    mouse_report_not_yet_sent = report;
+    osalSysUnlock();
+    return;
+  }
   usbStartTransmitI(&USB_DRIVER, MOUSE_ENDPOINT, (uint8_t *)report, sizeof(report_mouse_t));
   osalSysUnlock();
 }
@@ -1216,9 +1222,12 @@ void send_mouse(report_mouse_t *report) {
 
 /* extrakey IN callback hander */
 void extra_in_cb(USBDriver *usbp, usbep_t ep) {
-  /* STUB */
-  (void)usbp;
-  (void)ep;
+  if (extra_report_waiting) {
+    osalSysLockFromISR();
+    usbStartTransmitI(usbp, ep, (uint8_t *)&extra_report_not_yet_sent, sizeof(report_extra_t));
+    extra_report_waiting = FALSE;
+    osalSysUnlockFromISR();
+  }
 }
 
 static void send_extra_report(uint8_t report_id, uint16_t data) {
@@ -1233,6 +1242,12 @@ static void send_extra_report(uint8_t report_id, uint16_t data) {
     .usage = data
   };
 
+  if (usbGetTransmitStatusI(&USB_DRIVER, EXTRA_ENDPOINT)) {
+    extra_report_not_yet_sent = report;
+    extra_report_waiting = TRUE;
+    osalSysUnlock();
+    return;
+  }
   usbStartTransmitI(&USB_DRIVER, EXTRA_ENDPOINT, (uint8_t *)&report, sizeof(report_extra_t));
   osalSysUnlock();
 }