diff --git a/localization_log_gamma_model.py b/localization_log_gamma_model.py
index 1fbcc4e..414e509 100644
--- a/localization_log_gamma_model.py
+++ b/localization_log_gamma_model.py
@@ -123,7 +123,7 @@ def main(args):
         filepaths.extend(["{}/{}".format(args.folderpath, file) for file in files if '.pickle' in file and '_floormap.pickle' not in file])
 
     # prepare
-    if args.outputfile:
+    if args.outputfile and not os.path.isfile(args.outputfile):
         with open(args.outputfile, 'w') as f:
             f.write("filename,true_x,true_y,est_tx_x,est_tx_y,error,est_tx_pwr,env_gamma,fit_mse,rss_diff_5perc,rss_diff_95perc,rss_diff_med,rss_diff_avg\n")