diff --git a/src/libsystemd/sd-event/test-event.c b/src/libsystemd/sd-event/test-event.c
index eb986c9e08..16bbd1296b 100644
--- a/src/libsystemd/sd-event/test-event.c
+++ b/src/libsystemd/sd-event/test-event.c
@@ -1075,7 +1075,7 @@ static int exit_on_idle_defer_handler(sd_event_source *s, void *userdata) {
 
         /* Disable ourselves, which should trigger exit-on-idle after the second iteration */
         if (*c == 2)
-                sd_event_source_set_enabled(s, SD_EVENT_OFF);
+                ASSERT_OK(sd_event_source_set_enabled(s, SD_EVENT_OFF));
 
         return 0;
 }