diff --git a/glib/FileUtils.cs b/glib/FileUtils.cs
index 0a96a6e34..153ee8726 100644
--- a/glib/FileUtils.cs
+++ b/glib/FileUtils.cs
@@ -25,5 +25,7 @@ namespace GLib {
 
 			return Marshal.PtrToStringAnsi (contents, length);
 		}
+
+		private FileUtils () {}
 	}
 }
diff --git a/glib/Log.cs b/glib/Log.cs
index d7c253479..498889d2c 100644
--- a/glib/Log.cs
+++ b/glib/Log.cs
@@ -20,7 +20,7 @@ namespace GLib {
 	public delegate void PrintFunc (string message);
 
 	[Flags]
-	public enum LogLevelFlags : uint
+	public enum LogLevelFlags : int
 	{
 		/* log flags */
 		FlagRecursion          = 1 << 0,
@@ -40,7 +40,7 @@ namespace GLib {
 		All                    = 255,
 
 		FlagMask               = 3,
-		LevelMask              = (uint) 0xFFFFFFFC
+		LevelMask              = unchecked ((int) 0xFFFFFFFC)
 	}
 
 	public class Log {
diff --git a/glib/Markup.cs b/glib/Markup.cs
index 5958e4a41..4bdd43aa0 100644
--- a/glib/Markup.cs
+++ b/glib/Markup.cs
@@ -13,6 +13,8 @@ namespace GLib {
 
 
 	public class Markup {
+		private Markup () {}
+		
 		[DllImport("libglib-2.0-0.dll")]
 		static extern IntPtr g_markup_escape_text (string text, int len);
 		
diff --git a/glib/Marshaller.cs b/glib/Marshaller.cs
index a563602f2..003255009 100644
--- a/glib/Marshaller.cs
+++ b/glib/Marshaller.cs
@@ -17,7 +17,12 @@ namespace GLibSharp {
 	/// </remarks>
 	
 	public class Marshaller {
-	
+
+		//
+		// Do not allow instances of this
+		//
+		private Marshaller () {}
+		
 		[DllImport("libglib-2.0-0.dll")]
 		static extern void g_free (IntPtr mem);
 
diff --git a/glib/Object.cs b/glib/Object.cs
index af5b4eefe..6521bc67b 100644
--- a/glib/Object.cs
+++ b/glib/Object.cs
@@ -16,7 +16,7 @@ namespace GLib {
 	using System.Runtime.InteropServices;
 
 	[AttributeUsage(AttributeTargets.All)]
-	public class WrapperClassAttribute : Attribute {
+	public sealed class WrapperClassAttribute : Attribute {
 
 		public WrapperClassAttribute () : base () {}
 	}
diff --git a/glib/SignalAttribute.cs b/glib/SignalAttribute.cs
index d69fcb641..8d55bcb66 100644
--- a/glib/SignalAttribute.cs
+++ b/glib/SignalAttribute.cs
@@ -20,7 +20,7 @@ namespace GLib {
 	///   and allows obtaining its original name.
 	/// </remarks>
 	[Serializable]
-	public class SignalAttribute : Attribute 
+	public sealed class SignalAttribute : Attribute 
 	{
 		private string cname;
 
diff --git a/glib/SignalCallback.cs b/glib/SignalCallback.cs
index f267176bf..463bbe717 100644
--- a/glib/SignalCallback.cs
+++ b/glib/SignalCallback.cs
@@ -40,7 +40,7 @@ namespace GtkSharp {
 		///	Initializes instance data.
 		/// </remarks>
 
-		public SignalCallback (GLib.Object obj, Delegate eh, System.Type argstype)
+		protected SignalCallback (GLib.Object obj, Delegate eh, System.Type argstype)
 		{
 			_key = _NextKey++;
 			_obj = obj;
diff --git a/glib/Source.cs b/glib/Source.cs
index 9431cfea2..570493eb5 100644
--- a/glib/Source.cs
+++ b/glib/Source.cs
@@ -10,6 +10,7 @@ namespace GLib {
 	using System.Runtime.InteropServices;
 
         public class Source {
+		private Source () {}
 		
 		[DllImport("libglib-2.0-0.dll")]
 		static extern bool g_source_remove (uint tag);
diff --git a/glib/Thread.cs b/glib/Thread.cs
index 7ad7fd8d7..6f39c79bb 100644
--- a/glib/Thread.cs
+++ b/glib/Thread.cs
@@ -11,6 +11,8 @@ namespace GLib
 
 	public class Thread
 	{
+		private Thread () {}
+		
 		[DllImport("libgthread-2.0-0.dll")]
 		static extern void g_thread_init (IntPtr i);
 
diff --git a/glib/Timeout.cs b/glib/Timeout.cs
index 514740e6c..f28b7665e 100755
--- a/glib/Timeout.cs
+++ b/glib/Timeout.cs
@@ -32,6 +32,7 @@ namespace GLib {
 
 	public class Timeout {
 
+		private Timeout () {} 
 		[DllImport("libglib-2.0-0.dll")]
 		static extern uint g_timeout_add (uint interval, TimeoutHandler d, IntPtr data);
 
diff --git a/glib/TypeConverter.cs b/glib/TypeConverter.cs
index ad1f49ec5..603baa030 100644
--- a/glib/TypeConverter.cs
+++ b/glib/TypeConverter.cs
@@ -17,6 +17,9 @@ namespace GLibSharp {
 	///  Utilities for converting between TypeFundamentals and System.Type
 	/// </remarks>
 	public class TypeConverter {
+
+		private TypeConverter () {}
+		
 		public static TypeFundamentals LookupType (System.Type type)
 		{
 			if (type.Equals (typeof (string)))