diff --git a/Source/Libs/GLibSharp/Marshaller.cs b/Source/Libs/GLibSharp/Marshaller.cs
index 449e5b7f3..3603a50d9 100644
--- a/Source/Libs/GLibSharp/Marshaller.cs
+++ b/Source/Libs/GLibSharp/Marshaller.cs
@@ -117,7 +117,7 @@ namespace GLib {
 			return ret;
 		}
 		[UnmanagedFunctionPointer(CallingConvention.Cdecl)]
-		delegate IntPtr d_g_filename_from_utf8(IntPtr mem, int len, IntPtr read, out IntPtr written, out IntPtr error);
+		delegate IntPtr d_g_filename_from_utf8(IntPtr mem, IntPtr len, IntPtr read, out IntPtr written, out IntPtr error);
 		static d_g_filename_from_utf8 g_filename_from_utf8 = FuncLoader.LoadFunction<d_g_filename_from_utf8>(FuncLoader.GetProcAddress(GLibrary.Load(Library.GLib), "g_filename_from_utf8"));
 
 		public static IntPtr StringToFilenamePtr (string str) 
@@ -125,9 +125,8 @@ namespace GLib {
 			if (str == null)
 				return IntPtr.Zero;
 
-			IntPtr dummy, error;
 			IntPtr utf8 = StringToPtrGStrdup (str);
-			IntPtr result = g_filename_from_utf8 (utf8, -1, IntPtr.Zero, out dummy, out error);
+			IntPtr result = g_filename_from_utf8 (utf8, (IntPtr)(-1), IntPtr.Zero, out _, out var error);
 
 			g_free (utf8);
 			if (error != IntPtr.Zero)