doc: Document assert_not_in_set().
diff --git a/include/cmocka.h b/include/cmocka.h
index 49af082..1a823de 100755
--- a/include/cmocka.h
+++ b/include/cmocka.h
@@ -594,9 +594,24 @@
_assert_in_set(value, values, number_of_values, __FILE__, __LINE__)
#endif
-/* Assert that the specified value is not within a set. */
+#ifdef DOXYGEN
+/**
+ * @brief Assert that the specified value is not within a set.
+ *
+ * The function prints an error message to standard error and terminates the
+ * test by calling fail() if value is within a set.
+ *
+ * @param[in] value The value to look up
+ *
+ * @param[in] values[] The array to check for the value.
+ *
+ * @param[in] count The size of the values array.
+ */
+void assert_not_in_set(uintmax_t value, uintmax_t values[], size_t count);
+#else
#define assert_not_in_set(value, values, number_of_values) \
_assert_not_in_set(value, values, number_of_values, __FILE__, __LINE__)
+#endif
/** @} */
