diff --git a/mimicmotion/dwpose/jit_pose.py b/mimicmotion/dwpose/jit_pose.py
index 7a7b6ac..feab1ff 100644
--- a/mimicmotion/dwpose/jit_pose.py
+++ b/mimicmotion/dwpose/jit_pose.py
@@ -22,7 +22,7 @@ def preprocess(
     # get shape of image
     img_shape = img.shape[:2]
     out_img, out_center, out_scale = [], [], []
-    if len(out_bbox) == 0:
+    if out_bbox is None or len(out_bbox) == 0:
         out_bbox = [[0, 0, img_shape[1], img_shape[0]]]
     for i in range(len(out_bbox)):
         x0 = out_bbox[i][0]
@@ -360,4 +360,4 @@ def inference_pose(model, out_bbox, oriImg, model_input_size=(288, 384)):
 
     keypoints, scores = postprocess(outputs, model_input_size, center, scale)
 
-    return keypoints, scores
\ No newline at end of file
+    return keypoints, scores