diff --git a/doc/api/fs.md b/doc/api/fs.md
index 53e650ac074891..255ee9c88cb059 100644
--- a/doc/api/fs.md
+++ b/doc/api/fs.md
@@ -3789,8 +3789,8 @@ Change the file system timestamps of the object referenced by `path`.
 
 The `atime` and `mtime` arguments follow these rules:
 
-* Values can be either numbers representing Unix epoch time, `Date`s, or a
-  numeric string like `'123456789.0'`.
+* Values can be either numbers representing Unix epoch time in seconds,
+  `Date`s, or a numeric string like `'123456789.0'`.
 * If the value can not be converted to a number, or is `NaN`, `Infinity` or
   `-Infinity`, an `Error` will be thrown.