diff --git a/src/openvpnserv/validate.c b/src/openvpnserv/validate.c
index 6a13a06..2858f62 100644
--- a/src/openvpnserv/validate.c
+++ b/src/openvpnserv/validate.c
@@ -227,6 +227,7 @@
     {
         MsgToEventLog(M_SYSERR, L"GetTokenInformation");
         free(groups);
+        groups = NULL;
     }
     return groups;
 }