diff --git a/glnx-dirfd.c b/glnx-dirfd.c
index 4a071cc7..95d7fe17 100644
--- a/glnx-dirfd.c
+++ b/glnx-dirfd.c
@@ -299,7 +299,7 @@ glnx_gen_temp_name (gchar *tmpl)
 
   g_return_if_fail (tmpl != NULL);
   len = strlen (tmpl);
-  g_return_if_fail (len < 6);
+  g_return_if_fail (len >= 6);
 
   XXXXXX = tmpl + (len - 6);