diff --git a/dbus/dbus-test-tap.c b/dbus/dbus-test-tap.c
index 710e5eb8..b728fa11 100644
--- a/dbus/dbus-test-tap.c
+++ b/dbus/dbus-test-tap.c
@@ -75,6 +75,7 @@ _dbus_test_diag (const char *format,
   vprintf (format, ap);
   va_end (ap);
   printf ("\n");
+  fflush (stdout);
 }
 
 /*