2 files changed, 3 insertions, 0 deletions
diff --git a/src/libstd/ffi/c_str.rs b/src/libstd/ffi/c_str.rs
index 2d5e8c04194..1c449712e1f 100644
--- a/src/libstd/ffi/c_str.rs
+++ b/src/libstd/ffi/c_str.rs
@@ -361,6 +361,7 @@ impl<'a> Default for &'a CStr {
 
 #[stable(feature = "cstr_default", since = "1.10.0")]
 impl Default for CString {
+    /// Creates an empty `CString`.
     fn default() -> CString {
         let a: &CStr = Default::default();
         a.to_owned()
diff --git a/src/libstd/ffi/os_str.rs b/src/libstd/ffi/os_str.rs
index 36cf4ef758d..d93d3c73622 100644
--- a/src/libstd/ffi/os_str.rs
+++ b/src/libstd/ffi/os_str.rs
@@ -170,6 +170,7 @@ impl ops::Deref for OsString {
 
 #[stable(feature = "osstring_default", since = "1.9.0")]
 impl Default for OsString {
+    /// Constructs an empty `OsString`.
     #[inline]
     fn default() -> OsString {
         OsString::new()
@@ -342,6 +343,7 @@ impl OsStr {
 
 #[stable(feature = "osstring_default", since = "1.9.0")]
 impl<'a> Default for &'a OsStr {
+    /// Creates an empty `OsStr`.
     #[inline]
     fn default() -> &'a OsStr {
         OsStr::new("")