diff --git a/mmdet/core/anchor/guided_anchor_target.py b/mmdet/core/anchor/guided_anchor_target.py
index bf43850b6d15689fae7d5a5d900cb9f1a7a61d37..21162eb9e894993626d2f24db853ebe6681b392a 100644
--- a/mmdet/core/anchor/guided_anchor_target.py
+++ b/mmdet/core/anchor/guided_anchor_target.py
@@ -250,7 +250,7 @@ def ga_shape_target_single(flat_approxs,
         tuple
     """
     if not inside_flags.any():
-        return (None, ) * 6
+        return (None, ) * 5
     # assign gt and sample anchors
     expand_inside_flags = inside_flags[:, None].expand(
         -1, approxs_per_octave).reshape(-1)