diff --git a/src/userprog/process.c b/src/userprog/process.c
index cecedc1..20f2f3c 100644
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -85,12 +85,11 @@ process_execute (const char *cmd)
 /* NOTE: Currently, the file being executed is closed in load () and then 
           reopened here. Because load is an exported public function, this
           might be necessary. */
-struct file *exec_file = filesys_open (file_name);
-file_deny_write (exec_file);
-
-/* Validates that the current file to be executed is a valid file */
-if (filesys_open (file_name) == NULL)
-    return TID_ERROR;
+  lock_acquire (&filesys_lock);
+  /* Validates that the current file to be executed is a valid file */
+  if (filesys_open (file_name) == NULL)
+      return TID_ERROR;
+  lock_release (&filesys_lock);
 
   /* Create a new thread to execute the command, by initializing
      it running the function 'start_process' with the appropriate