diff --git a/tools/releasetools/img_from_target_files b/tools/releasetools/img_from_target_files
index 1f119ad..0c4c859 100755
--- a/tools/releasetools/img_from_target_files
+++ b/tools/releasetools/img_from_target_files
@@ -130,9 +130,19 @@
     build_command.append(os.path.join(OPTIONS.input_tmp, "system"))
     build_command.append(img.name)
 
-  p = common.Run(build_command)
-  p.communicate()
-  assert p.returncode == 0, "build system.img image failed"
+  # p = common.Run(build_command)
+  # p.communicate()
+  # assert p.returncode == 0, "build system.img image failed"
+
+  # TODO: Why the above common.Run() generate different system.img for crespo?
+  str_command = "mkyaffs2image -f ";
+  if OPTIONS.mkyaffs2_extra_flags is not None:
+    str_command = str_command + OPTIONS.mkyaffs2_extra_flags
+  str_command = str_command + " " + os.path.join(OPTIONS.input_tmp, "system") + " " + img.name
+
+  print "running " + str_command
+  exit_code = os.system(str_command)
+  assert exit_code == 0, "build system.img image failed"
 
   img.seek(os.SEEK_SET, 0)
   data = img.read()