diff --git a/localization_log_gamma_model.py b/localization_log_gamma_model.py
index 7fce6af..e2dd9a6 100644
--- a/localization_log_gamma_model.py
+++ b/localization_log_gamma_model.py
@@ -33,8 +33,9 @@ def fittingSingle(filepath, args):
         return
     location_gt = [float('nan'), float('nan')]
     if len(data) is 2:
-        data, location_gt = data
-        location_gt = location_gt * 0.1
+        data, location_gt_tmp = data
+        if location_gt_tmp is not None:
+            location_gt = location_gt_tmp * 0.1
 
     # convert data matrix to vectors
     rx_locs, rx_rsses = convert_mat_to_vector(data, block_size=0.1)