diff --git a/src/engine.c b/src/engine.c
index 699c59c6a8110be5b557b97dfef27e30ecd4f198..7f3e562f8a4f577efe62cd855b1ea2f80dfcc827 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -1969,7 +1969,8 @@ void engine_makeproxies(struct engine *e) {
  * @brief Split the underlying space according to the given grid.
  *
  * @param e The #engine.
- * @param grid The grid.
+ * @param ipart initpart structure define the partition technique and any
+ *              additional metadata.
  */
 
 void engine_split(struct engine *e, struct initpart *ipart) {