diff --git a/glib/GInterfaceAdapter.cs b/glib/GInterfaceAdapter.cs
index d76be76a6..7b3c60064 100644
--- a/glib/GInterfaceAdapter.cs
+++ b/glib/GInterfaceAdapter.cs
@@ -24,8 +24,10 @@ namespace GLib {
 	using System;
 	using System.Runtime.InteropServices;
 
+	[UnmanagedFunctionPointer (CallingConvention.Cdecl)]
 	public delegate void GInterfaceInitHandler (IntPtr iface_ptr, IntPtr data);
 
+	[UnmanagedFunctionPointer (CallingConvention.Cdecl)]
 	internal delegate void GInterfaceFinalizeHandler (IntPtr iface_ptr, IntPtr data);
 
 	internal struct GInterfaceInfo {