diff --git a/src/testing/testing_api_cmd_exec_wirewatch.c b/src/testing/testing_api_cmd_exec_wirewatch.c
index 44de96838..7a1a27a51 100644
--- a/src/testing/testing_api_cmd_exec_wirewatch.c
+++ b/src/testing/testing_api_cmd_exec_wirewatch.c
@@ -67,7 +67,7 @@ wirewatch_run (void *cls,
                                "taler-exchange-wirewatch",
                                "taler-exchange-wirewatch",
                                "-c", ws->config_filename,
-                               "-T", /* exit when done */
+                               "-t", /* exit when done */
                                NULL);
   if (NULL == ws->wirewatch_proc)
   {