diff --git a/core/include/cib.h b/core/include/cib.h
index f3a85363d9..087ec1c7a0 100644
--- a/core/include/cib.h
+++ b/core/include/cib.h
@@ -39,6 +39,10 @@ typedef struct {
 
 /**
  * @brief   Initialize cib_t to a given size.
+ *
+ * @param[in]  SIZE     Size of the buffer, must not exceed
+ *                      (`UINT_MAX` + 1) / 2.
+ *                      Should be equal to 0 or power of 2.
  */
 #define CIB_INIT(SIZE) { 0, 0, (SIZE)-1 }
 
@@ -47,7 +51,8 @@ typedef struct {
  *
  * @param[out] cib      Buffer to initialize.
  *                      Must not be NULL.
- * @param[in]  size     Size of the buffer, must not exceed MAXINT/2.
+ * @param[in]  size     Size of the buffer, must not exceed
+ *                      (`UINT_MAX` + 1) / 2.
  *                      Should be equal to 0 or power of 2.
  */
 static inline void cib_init(cib_t *__restrict cib, unsigned int size)