diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index 126bc3754dabc..56fde77daac58 100644
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -1819,6 +1819,8 @@ impl Path {
     /// Yields a [`&str`] slice if the `Path` is valid unicode.
     ///
     /// This conversion may entail doing a check for UTF-8 validity.
+    /// Note that validation is performed because non-UTF-8 strings are
+    /// perfectly valid for some OS.
     ///
     /// [`&str`]: ../primitive.str.html
     ///