diff --git a/gobject/gobject.h b/gobject/gobject.h
index bf5496c54..7f55e1976 100644
--- a/gobject/gobject.h
+++ b/gobject/gobject.h
@@ -679,16 +679,16 @@ void    g_clear_object (GObject **object_ptr);
 
 /**
  * g_set_object: (skip)
- * @object_ptr: a pointer to a #GObject reference
+ * @object_ptr: (inout) (not optional) (nullable): a pointer to a #GObject reference
  * @new_object: (nullable) (transfer none): a pointer to the new #GObject to
- *   assign to it, or %NULL to clear the pointer
+ *   assign to @object_ptr, or %NULL to clear the pointer
  *
  * Updates a #GObject pointer to refer to @new_object. It increments the
  * reference count of @new_object (if non-%NULL), decrements the reference
  * count of the current value of @object_ptr (if non-%NULL), and assigns
  * @new_object to @object_ptr. The assignment is not atomic.
  *
- * @object_ptr must not be %NULL.
+ * @object_ptr must not be %NULL, but can point to a %NULL value.
  *
  * A macro is also included that allows this function to be used without
  * pointer casts. The function itself is static inline, so its address may vary