diff --git a/testcode/perf.c b/testcode/perf.c
index 8e4c5fe91..d6d2b0529 100644
--- a/testcode/perf.c
+++ b/testcode/perf.c
@@ -513,10 +513,10 @@ qlist_grow_capacity(struct perfinfo* info)
 	uint8_t** d = (uint8_t**)calloc(sizeof(uint8_t*), newcap);
 	size_t* l = (size_t*)calloc(sizeof(size_t), newcap);
 	if(!d || !l) fatal_exit("out of memory");
-	if(info->qlist_data)
+	if(info->qlist_data && info->qlist_capacity)
 		memcpy(d, info->qlist_data, sizeof(uint8_t*)*
 			info->qlist_capacity);
-	if(info->qlist_len)
+	if(info->qlist_len && info->qlist_capacity)
 		memcpy(l, info->qlist_len, sizeof(size_t)*
 			info->qlist_capacity);
 	free(info->qlist_data);