diff --git a/core/include/atomic.h b/core/include/atomic.h
index 5fb20fc1d0..07d663cbd4 100644
--- a/core/include/atomic.h
+++ b/core/include/atomic.h
@@ -27,6 +27,9 @@ extern "C" {
 
 /**
  * @brief Integer variable for use in atomic counters.
+ *
+ * @note    This type is a struct for hard type checking (let the compiler warn
+ *          if int is assigned regularly).
  */
 typedef struct atomic_int {
     volatile int value;         /**< the actual value */