diff --git a/Cargo.toml b/Cargo.toml
index cfb70da1..732cecb7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -58,5 +58,5 @@ gobject-sys = { git = "https://github.com/gtk-rs/sys" }
 
 [dev-dependencies]
 gir-format-check = "^0.1"
-serial_test = "0.1"
-serial_test_derive = "0.1"
+serial_test = "0.4"
+serial_test_derive = "0.4"
diff --git a/Gir.toml b/Gir.toml
index ae568ff2..b5957925 100644
--- a/Gir.toml
+++ b/Gir.toml
@@ -310,6 +310,8 @@ status = "generate"
     [[object.function]]
     name = "get_unix_user"
     cfg_condition = "unix"
+        [object.function.return]
+        use_return_for_result = true
     [[object.function]]
     name = "set_unix_user"
     cfg_condition = "unix"
diff --git a/gir b/gir
index 0a4cfc40..5467258a 160000
--- a/gir
+++ b/gir
@@ -1 +1 @@
-Subproject commit 0a4cfc40553744bd831d6c1f5fcb58de0dd01485
+Subproject commit 5467258a70f37e865f1f8ea944937137c1762b0f
diff --git a/gir-files b/gir-files
index 22748fa8..480c1170 160000
--- a/gir-files
+++ b/gir-files
@@ -1 +1 @@
-Subproject commit 22748fa889ff60b97e53966c31693a73a6249f82
+Subproject commit 480c1170b74e22f41fd88b69f80856d1617d5dcf
diff --git a/src/auto/credentials.rs b/src/auto/credentials.rs
index 3eaa4fe0..5b844ad8 100644
--- a/src/auto/credentials.rs
+++ b/src/auto/credentials.rs
@@ -40,12 +40,12 @@ impl Credentials {
     }
 
     #[cfg(any(unix, feature = "dox"))]
-    pub fn get_unix_user(&self) -> Result<(), glib::Error> {
+    pub fn get_unix_user(&self) -> Result<u32, glib::Error> {
         unsafe {
             let mut error = ptr::null_mut();
-            let _ = gio_sys::g_credentials_get_unix_user(self.to_glib_none().0, &mut error);
+            let ret = gio_sys::g_credentials_get_unix_user(self.to_glib_none().0, &mut error);
             if error.is_null() {
-                Ok(())
+                Ok(ret)
             } else {
                 Err(from_glib_full(error))
             }
diff --git a/src/auto/versions.txt b/src/auto/versions.txt
index 925d92d3..2109f1a4 100644
--- a/src/auto/versions.txt
+++ b/src/auto/versions.txt
@@ -1,2 +1,2 @@
-Generated by gir (https://github.com/gtk-rs/gir @ 0a4cfc4)
-from gir-files (https://github.com/gtk-rs/gir-files @ 22748fa)
+Generated by gir (https://github.com/gtk-rs/gir @ 5467258)
+from gir-files (https://github.com/gtk-rs/gir-files @ 480c117)
diff --git a/src/subclass/mod.rs b/src/subclass/mod.rs
index a79449e9..0f348c87 100644
--- a/src/subclass/mod.rs
+++ b/src/subclass/mod.rs
@@ -2,17 +2,20 @@
 // See the COPYRIGHT file at the top-level directory of this distribution.
 // Licensed under the MIT license, see the LICENSE file or <http://opensource.org/licenses/MIT>
 
-pub mod application;
-pub mod input_stream;
-pub mod io_stream;
-pub mod output_stream;
-pub mod seekable;
+mod application;
+mod input_stream;
+mod io_stream;
+mod output_stream;
+mod seekable;
+
+pub use self::application::ArgumentList;
+pub use self::prelude::*;
 
 pub mod prelude {
-    pub use super::application::{ApplicationImpl, ArgumentList};
-    pub use super::input_stream::InputStreamImpl;
-    pub use super::io_stream::IOStreamImpl;
-    pub use super::output_stream::OutputStreamImpl;
+    pub use super::application::{ApplicationImpl, ApplicationImplExt};
+    pub use super::input_stream::{InputStreamImpl, InputStreamImplExt};
+    pub use super::io_stream::{IOStreamImpl, IOStreamImplExt};
+    pub use super::output_stream::{OutputStreamImpl, OutputStreamImplExt};
     pub use super::seekable::SeekableImpl;
     pub use glib::subclass::prelude::*;
 }