diff --git a/servers/slapd/back-monitor/thread.c b/servers/slapd/back-monitor/thread.c
index 4c90f05210..5fdbd071e9 100644
--- a/servers/slapd/back-monitor/thread.c
+++ b/servers/slapd/back-monitor/thread.c
@@ -260,6 +260,7 @@ monitor_subsys_thread_update(
 				ber_bvarray_free( a->a_vals );
 				a->a_vals = NULL;
 				a->a_nvals = NULL;
+				a->a_numvals = 0;
 			}
 
 			i = 0;
@@ -292,6 +293,7 @@ monitor_subsys_thread_update(
 				ber_bvarray_free( a->a_vals );
 				a->a_vals = NULL;
 				a->a_nvals = NULL;
+				a->a_numvals = 0;
 			}
 	
 			i = 0;