diff --git a/src/libstd/sys/unix/ext/fs.rs b/src/libstd/sys/unix/ext/fs.rs
index 96c0f4eab427..3e631ad40ac7 100644
--- a/src/libstd/sys/unix/ext/fs.rs
+++ b/src/libstd/sys/unix/ext/fs.rs
@@ -68,8 +68,8 @@ fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
 /// Unix-specific extensions to `Permissions`
 #[stable(feature = "fs_ext", since = "1.1.0")]
 pub trait PermissionsExt {
-    /// Returns the 12 least significant bits of `st_mode` which are the
-    /// standard Unix permissions for this file.
+    /// Returns the underlying raw `st_mode` bits that contain the standard
+    /// Unix permissions for this file.
     ///
     /// # Examples
     ///
diff --git a/src/libstd/sys/unix/fs.rs b/src/libstd/sys/unix/fs.rs
index e0ce02873f5c..c4616c3b395b 100644
--- a/src/libstd/sys/unix/fs.rs
+++ b/src/libstd/sys/unix/fs.rs
@@ -95,7 +95,7 @@ pub struct DirBuilder { mode: mode_t }
 impl FileAttr {
     pub fn size(&self) -> u64 { self.stat.st_size as u64 }
     pub fn perm(&self) -> FilePermissions {
-        FilePermissions { mode: (self.stat.st_mode as mode_t) & 0o7777 }
+        FilePermissions { mode: (self.stat.st_mode as mode_t) }
     }
 
     pub fn file_type(&self) -> FileType {