diff --git a/src/engine.c b/src/engine.c
index 17bf347d00b82fffbe4d863748ccaae9c2f92983..8e5c963e82d0d0aee3e1a6fc6f4de823de19465c 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -2637,6 +2637,7 @@ void engine_init_particles(struct engine *e, int flag_entropy_ICs) {
 
   /* Ready to go */
   e->step = -1;
+  e->forcerebuild = 1;
   e->wallclock_time = (float)clocks_diff(&time1, &time2);
 
   if (e->verbose) message("took %.3f %s.", e->wallclock_time, clocks_getunit());