diff --git a/detectron/datasets/json_dataset.py b/detectron/datasets/json_dataset.py
index 7fc351613..bc1b26e49 100644
--- a/detectron/datasets/json_dataset.py
+++ b/detectron/datasets/json_dataset.py
@@ -145,7 +145,7 @@ def _prep_roidb_entry(self, entry):
         entry['gt_overlaps'] = scipy.sparse.csr_matrix(
             np.empty((0, self.num_classes), dtype=np.float32)
         )
-        entry['is_crowd'] = np.empty((0), dtype=np.bool)
+        entry['is_crowd'] = np.empty((0), dtype=bool)
         # 'box_to_gt_ind_map': Shape is (#rois). Maps from each roi to the index
         # in the list of rois that satisfy np.where(entry['gt_classes'] > 0)
         entry['box_to_gt_ind_map'] = np.empty((0), dtype=np.int32)
diff --git a/detectron/datasets/voc_eval.py b/detectron/datasets/voc_eval.py
index 1497305de..d4cee7cfd 100644
--- a/detectron/datasets/voc_eval.py
+++ b/detectron/datasets/voc_eval.py
@@ -148,7 +148,7 @@ def voc_eval(detpath,
     for imagename in imagenames:
         R = [obj for obj in recs[imagename] if obj['name'] == classname]
         bbox = np.array([x['bbox'] for x in R])
-        difficult = np.array([x['difficult'] for x in R]).astype(np.bool)
+        difficult = np.array([x['difficult'] for x in R]).astype(bool)
         det = [False] * len(R)
         npos = npos + sum(~difficult)
         class_recs[imagename] = {'bbox': bbox,