diff --git a/src/userprog/syscall.c b/src/userprog/syscall.c
index 102458f..f0aaf47 100644
--- a/src/userprog/syscall.c
+++ b/src/userprog/syscall.c
@@ -193,10 +193,17 @@ syscall_open (const char *file)
 }
 
 static int
-syscall_filesize (int fd UNUSED)
+syscall_filesize (int fd)
 {
-  //TODO
-  return 0;
+  struct open_file *file_info = fd_get_file (fd);
+  if (file_info == NULL)
+      return -1;
+
+  lock_acquire (&filesys_lock);
+  int bytes = file_length (file_info->file);
+  lock_release (&filesys_lock);
+
+  return bytes;
 }
 
 static int
@@ -261,10 +268,17 @@ syscall_seek (int fd, unsigned position)
 }
 
 static unsigned
-syscall_tell (int fd UNUSED)
+syscall_tell (int fd)
 {
-  //TODO
-  return 0;
+  struct open_file *file_info = fd_get_file (fd);
+  if (file_info == NULL)
+    return 0;
+
+  lock_acquire (&filesys_lock);
+  unsigned pos = file_tell (file_info->file);
+  lock_release (&filesys_lock);
+
+  return pos;
 }
 
 static void