diff --git a/tools/infer/predict_rec.py b/tools/infer/predict_rec.py
index b1538938ab81349f7f6708c025419f8ca78bba73..9761ddbad9123372d706db158aba8008956f30e9 100755
--- a/tools/infer/predict_rec.py
+++ b/tools/infer/predict_rec.py
@@ -122,7 +122,7 @@ class TextRecognizer(object):
                     blank = probs.shape[1]
                     valid_ind = np.where(ind != (blank - 1))[0]
                     score = np.mean(probs[valid_ind, ind[valid_ind]])
-                    if not valid_ind:
+                    if len(valid_ind) == 0:
                         continue
                     # rec_res.append([preds_text, score])
                     rec_res[indices[beg_img_no + rno]] = [preds_text, score]
diff --git a/tools/infer_rec.py b/tools/infer_rec.py
index 6086e4997d58aef907974a75539cdb538e25e54b..9abbf076e9a4902cdd0876c320021fc45e227a2c 100755
--- a/tools/infer_rec.py
+++ b/tools/infer_rec.py
@@ -99,7 +99,7 @@ def main():
             ind = np.argmax(probs, axis=1)
             blank = probs.shape[1]
             valid_ind = np.where(ind != (blank - 1))[0]
-            if not valid_ind:
+            if len(valid_ind) == 0:
                 continue
             score = np.mean(probs[valid_ind, ind[valid_ind]])
         elif loss_type == "attention":