diff --git a/web/api/formatters/rrd2json.c b/web/api/formatters/rrd2json.c
index 7bb7544cfe..45ec3c2030 100644
--- a/web/api/formatters/rrd2json.c
+++ b/web/api/formatters/rrd2json.c
@@ -45,12 +45,12 @@ void build_context_param_list(struct context_param **param_list, RRDSET *st)
     }
 
     RRDDIM *rd1;
-    rrdset_rdlock(st);
-
-    st->last_accessed_time = now_realtime_sec();
     (*param_list)->first_entry_t = MIN((*param_list)->first_entry_t, rrdset_first_entry_t(st));
     (*param_list)->last_entry_t  = MAX((*param_list)->last_entry_t, rrdset_last_entry_t(st));
 
+    st->last_accessed_time = now_realtime_sec();
+    rrdset_rdlock(st);
+
     rrddim_foreach_read(rd1, st) {
         RRDDIM *rd = mallocz(rd1->memsize);
         memcpy(rd, rd1, rd1->memsize);