diff --git a/plugins/sudoers/gram.c b/plugins/sudoers/gram.c
index e5f1ca3d5..b3dc644ce 100644
--- a/plugins/sudoers/gram.c
+++ b/plugins/sudoers/gram.c
@@ -3974,6 +3974,7 @@ free_parse_tree(struct sudoers_parse_tree *parse_tree)
     if (parse_tree->shost != parse_tree->lhost)
 	free(parse_tree->shost);
     parse_tree->lhost = parse_tree->shost = NULL;
+    parse_tree->nss = NULL;
 }
 
 /*
diff --git a/plugins/sudoers/gram.y b/plugins/sudoers/gram.y
index 16244e6ae..6563d1f4a 100644
--- a/plugins/sudoers/gram.y
+++ b/plugins/sudoers/gram.y
@@ -1791,6 +1791,7 @@ free_parse_tree(struct sudoers_parse_tree *parse_tree)
     if (parse_tree->shost != parse_tree->lhost)
 	free(parse_tree->shost);
     parse_tree->lhost = parse_tree->shost = NULL;
+    parse_tree->nss = NULL;
 }
 
 /*