diff --git a/src/cell.h b/src/cell.h
index 021cdccf0823eae1294703a512a558764b767bef..899503997d1aa8f9f1c93690a07e41c02341cdb8 100644
--- a/src/cell.h
+++ b/src/cell.h
@@ -390,4 +390,6 @@ void cell_activate_subcell_tasks(struct cell *ci, struct cell *cj,
                                  struct scheduler *s);
 int cell_can_recurse_in_pair_task(const struct cell *c);
 int cell_can_split_task(const struct cell *c);
+int cell_need_rebuild_for_pair(const struct cell *ci, const struct cell *cj);
+
 #endif /* SWIFT_CELL_H */