diff --git a/os/kernel/include/chqueues.h b/os/kernel/include/chqueues.h
index 76a0b63a5..5a11ec7cc 100644
--- a/os/kernel/include/chqueues.h
+++ b/os/kernel/include/chqueues.h
@@ -205,7 +205,7 @@ typedef GenericQueue OutputQueue;
  *
  * @iclass
  */
-#define chOQIsEmptyI(q) ((bool_t)(chQSpaceI(q) >= chQSizeI(q)))
+#define chOQIsEmptyI(oqp) ((bool_t)(chQSpaceI(q) >= chQSizeI(q)))
 
 /**
  * @brief   Evaluates to @p TRUE if the specified output queue is full.
@@ -217,7 +217,7 @@ typedef GenericQueue OutputQueue;
  *
  * @iclass
  */
-#define chOQIsFullI(q) ((bool_t)(chQSpaceI(q) <= 0))
+#define chOQIsFullI(oqp) ((bool_t)(chQSpaceI(q) <= 0))
 
 /**
  * @brief   Output queue write.
diff --git a/os/kernel/src/chqueues.c b/os/kernel/src/chqueues.c
index 4a195fa9b..8d459a7e8 100644
--- a/os/kernel/src/chqueues.c
+++ b/os/kernel/src/chqueues.c
@@ -73,6 +73,8 @@ void chIQInit(InputQueue *iqp, uint8_t *bp, size_t size, qnotify_t infy) {
  * @brief   Returns the filled space into an input queue.
  *
  * @param[in] iqp       pointer to an @p InputQueue structure
+ * @return              The number of bytes in the queue.
+ * @retval 0            if the queue is empty.
  *
  * @iclass
  */
@@ -252,6 +254,8 @@ void chOQInit(OutputQueue *oqp, uint8_t *bp, size_t size, qnotify_t onfy) {
  * @brief   Returns the filled space into an output queue.
  *
  * @param[in] oqp       pointer to an @p OutputQueue structure
+ * @return              The number of bytes in the queue.
+ * @retval 0            if the queue is empty.
  *
  * @iclass
  */