diff --git a/src/tutorials/0004-mutable-file-system/05.md b/src/tutorials/0004-mutable-file-system/05.md
index e0e22ac9..331ee91d 100644
--- a/src/tutorials/0004-mutable-file-system/05.md
+++ b/src/tutorials/0004-mutable-file-system/05.md
@@ -28,7 +28,7 @@ contained in the directory you're inspecting, with the following properties:
 - `size`: the size of the file in bytes
 - `cid`: the Content Identifier (CID) that identifies your file in IPFS
 - `mode`: the UnixFS mode as a Number
-- `mtime`: an object with numeric `secs` and `nsecs` properties
+- `mtime`: a two-element structure (`secs`, `nsecs`) representing the modification time in seconds relative to the Unix epoch `1970-01-01T00:00:00Z`
 
 If we wanted to inspect the contents of a `/catPics`
 directory, we could do it like this: