diff --git a/tools/voc_eval.py b/tools/voc_eval.py
index 478ec3cf445068fd9295f3b33d0212e0a5b6456f..a86b13e856ff39418027dbd39f3287966ae0e171 100644
--- a/tools/voc_eval.py
+++ b/tools/voc_eval.py
@@ -27,7 +27,7 @@ def voc_eval(result_file, dataset, iou_thr=0.5):
         gt_bboxes.append(bboxes)
         gt_labels.append(labels)
     if not gt_ignore:
-        gt_ignore = gt_ignore
+        gt_ignore = None
     if hasattr(dataset, 'year') and dataset.year == 2007:
         dataset_name = 'voc07'
     else: