diff --git a/scripts/run_benchmark.py b/scripts/run_benchmark.py
index 7f67764e0..93d68ba4d 100755
--- a/scripts/run_benchmark.py
+++ b/scripts/run_benchmark.py
@@ -108,7 +108,7 @@ def obtain_model_file(self, model):
             for line in src_f.readlines():
                 if re.match(batch_size_pattern, line) and cnt < batch_size_cnt:
                    #change batch size
-                    re.sub("[0-9]+", new_batch_size, line, count = 1)
+                    line = re.sub("[0-9]+", new_batch_size, line, count = 1)
                     cnt += 1
                 dst_f.write(line) 
         return dst_model_file