diff --git a/src/engine_marktasks.c b/src/engine_marktasks.c
index 2206a9b8ecdf8b4b24b8f0287b12a7222b72fb8e..80fd0e335c2b07abe15f8149c058d9494f2a5a68 100644
--- a/src/engine_marktasks.c
+++ b/src/engine_marktasks.c
@@ -182,8 +182,10 @@ void engine_marktasks_mapper(void *map_data, int num_elements,
       const int cj_active_hydro = cell_is_active_hydro(cj, e);
       const int ci_active_gravity = cell_is_active_gravity(ci, e);
       const int cj_active_gravity = cell_is_active_gravity(cj, e);
-      const int ci_active_stars = cell_is_active_stars(ci, e);
-      const int cj_active_stars = cell_is_active_stars(cj, e);
+
+      // MATTHIEU: This is broken here. In cases with ext-potential this crashes.
+      const int ci_active_stars = 0;  // cell_is_active_stars(ci, e);
+      const int cj_active_stars = 0;  // cell_is_active_stars(cj, e);
 
       /* Only activate tasks that involve a local active cell. */
       if ((t_subtype == task_subtype_density ||