diff --git a/src/engine.c b/src/engine.c
index 866ac9055d53a95a16403adc06591a05d6f71aaf..9cdc85a0e8dcc34c5fd8597e95d9825f90d0d402 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -3361,6 +3361,7 @@ void engine_init(struct engine *e, struct space *s,
     }
 
     /* Allocate particle cache. */
+    e->runners[k].par_cache.count = 0;
     cache_init(&e->runners[k].par_cache,cache_size);
 
     if (verbose) {