diff --git a/Source/Libs/CairoSharp/Context.cs b/Source/Libs/CairoSharp/Context.cs
index 09de92921..a30c67c3a 100644
--- a/Source/Libs/CairoSharp/Context.cs
+++ b/Source/Libs/CairoSharp/Context.cs
@@ -53,7 +53,7 @@ namespace Cairo {
 
 		static int native_glyph_size, c_compiler_long_size;
 
-		static Context ()
+		static unsafe Context ()
 		{
 			//
 			// This is used to determine what kind of structure
@@ -65,7 +65,7 @@ namespace Cairo {
 			// except in the case of Win64 where sizeof(long)
 			// is 32 bits
 			//
-			int ptr_size = Marshal.SizeOf (typeof (IntPtr));
+			int ptr_size = sizeof(IntPtr);
 
 			PlatformID platform = Environment.OSVersion.Platform;
 			if (platform == PlatformID.Win32NT ||
@@ -74,10 +74,10 @@ namespace Cairo {
 			    platform == PlatformID.WinCE ||
 			    ptr_size == 4){
 				c_compiler_long_size = 4;
-				native_glyph_size = Marshal.SizeOf (typeof (NativeGlyph_4byte_longs));
+				native_glyph_size = Marshal.SizeOf<NativeGlyph_4byte_longs> ();
 			} else {
 				c_compiler_long_size = 8;
-				native_glyph_size = Marshal.SizeOf (typeof (Glyph));
+				native_glyph_size = Marshal.SizeOf<Glyph> ();
 			}
 		}
 
diff --git a/Source/Libs/CairoSharp/Glyph.cs b/Source/Libs/CairoSharp/Glyph.cs
index ec9c2ff38..a5efd9357 100644
--- a/Source/Libs/CairoSharp/Glyph.cs
+++ b/Source/Libs/CairoSharp/Glyph.cs
@@ -75,7 +75,7 @@ namespace Cairo
 
 		internal static IntPtr GlyphsToIntPtr (Glyph[] glyphs)
 		{
-			int size = Marshal.SizeOf (glyphs[0]);
+			int size = Marshal.SizeOf<Glyph> ();
 			IntPtr dest = Marshal.AllocHGlobal (size * glyphs.Length);
 			long pos = dest.ToInt64 ();
 			for (int i = 0; i < glyphs.Length; i++, pos += size)
diff --git a/Source/Libs/GLibSharp/HookList.cs b/Source/Libs/GLibSharp/HookList.cs
index 34df11c1f..7af30e4e3 100644
--- a/Source/Libs/GLibSharp/HookList.cs
+++ b/Source/Libs/GLibSharp/HookList.cs
@@ -12,10 +12,10 @@ namespace GLib {
 	public partial class HookList : GLib.Opaque {
 
 		// Internal representation of the wrapped ABI structure.
-		static public AbiStruct abi_info = new AbiStruct(new List<AbiField> {
+		static public unsafe AbiStruct abi_info = new AbiStruct(new List<AbiField> {
 				new GLib.AbiField("seq_id"
 						, 0
-						, (uint) Marshal.SizeOf(typeof(ulong)) // seq_id
+						, (uint) sizeof (ulong) // seq_id
 						, null
 						, "hook_size"
 						, (long) Marshal.OffsetOf(typeof(GHookList_seq_idAlign), "seq_id")
@@ -23,7 +23,7 @@ namespace GLib {
 						),
 				new GLib.AbiField("hook_size"
 						, -1
-						, (uint) Marshal.SizeOf(typeof(uint)) // hook_size
+						, (uint) sizeof (uint) // hook_size
 						, "seq_id"
 						, "is_setup"
 						, 1
@@ -31,7 +31,7 @@ namespace GLib {
 						),
 				new GLib.AbiField("is_setup"
 						, -1
-						, (uint) Marshal.SizeOf(typeof(bool)) // is_setup
+						, (uint) Marshal.SizeOf<bool>() // is_setup
 						, "hook_size"
 						, "hooks"
 						, 1
@@ -39,7 +39,7 @@ namespace GLib {
 						),
 				new GLib.AbiField("hooks"
 						, -1
-						, (uint) Marshal.SizeOf(typeof(IntPtr)) // hooks
+						, (uint) sizeof (IntPtr) // hooks
 						, "is_setup"
 						, "dummy3"
 						, (long) Marshal.OffsetOf(typeof(GHookList_hooksAlign), "hooks")
@@ -47,7 +47,7 @@ namespace GLib {
 						),
 				new GLib.AbiField("dummy3"
 						, -1
-						, (uint) Marshal.SizeOf(typeof(IntPtr)) // dummy3
+						, (uint) sizeof (IntPtr) // dummy3
 						, "hooks"
 						, "finalize_hook"
 						, (long) Marshal.OffsetOf(typeof(GHookList_dummy3Align), "dummy3")
@@ -55,7 +55,7 @@ namespace GLib {
 						),
 				new GLib.AbiField("finalize_hook"
 						, -1
-						, (uint) Marshal.SizeOf(typeof(IntPtr)) // finalize_hook
+						, (uint) sizeof (IntPtr) // finalize_hook
 						, "dummy3"
 						, "dummy"
 						, (long) Marshal.OffsetOf(typeof(GHookList_finalize_hookAlign), "finalize_hook")
@@ -63,7 +63,7 @@ namespace GLib {
 						),
 				new GLib.AbiField("dummy"
 						, -1
-						, (uint) Marshal.SizeOf(typeof(IntPtr)) * 2 // dummy
+						, (uint) sizeof (IntPtr) * 2 // dummy
 						, "finalize_hook"
 						, null
 						, (long) Marshal.OffsetOf(typeof(GHookList_dummyAlign), "dummy")
diff --git a/Source/Libs/GLibSharp/Marshaller.cs b/Source/Libs/GLibSharp/Marshaller.cs
index def1d1f93..23af0cd4d 100644
--- a/Source/Libs/GLibSharp/Marshaller.cs
+++ b/Source/Libs/GLibSharp/Marshaller.cs
@@ -356,19 +356,19 @@ namespace GLib {
 			while (current != IntPtr.Zero) {
 				Marshal.PtrToStructure (current, currentStruct);
 				res.Add (currentStruct);
-				current = (IntPtr) ((long)current + Marshal.SizeOf (typeof (T)));
+				current = (IntPtr) ((long)current + Marshal.SizeOf<T> ());
 			}
 
 			return res.ToArray ();
 		}
 
-		public static IntPtr StructArrayToNullTerminatedStructArrayIntPtr<T> (T[] InputArray)
+		public static unsafe IntPtr StructArrayToNullTerminatedStructArrayIntPtr<T> (T[] InputArray)
 		{
-			int intPtrSize = Marshal.SizeOf (typeof (IntPtr));
+			int intPtrSize = sizeof (IntPtr);
 			IntPtr mem = Marshal.AllocHGlobal ((InputArray.Length + 1) * intPtrSize);
 
 			for (int i = 0; i < InputArray.Length; i++) {
-				IntPtr structPtr = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (T)));
+				IntPtr structPtr = Marshal.AllocHGlobal (Marshal.SizeOf<T> ());
 				Marshal.StructureToPtr (InputArray[i], structPtr, false);
 				// jump to next pointer
 				Marshal.WriteIntPtr (mem, structPtr);
diff --git a/Source/Libs/GLibSharp/Object.cs b/Source/Libs/GLibSharp/Object.cs
index 833b8e513..e75638754 100644
--- a/Source/Libs/GLibSharp/Object.cs
+++ b/Source/Libs/GLibSharp/Object.cs
@@ -936,10 +936,10 @@ namespace GLib {
 		}
 
 		// Internal representation of the wrapped ABI structure.
-		static public AbiStruct abi_info = new AbiStruct(new List<AbiField> {
+		static public unsafe AbiStruct abi_info = new AbiStruct(new List<AbiField> {
 				new GLib.AbiField("g_type_instance"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, null
 					, "ref_count"
 					, (long) Marshal.OffsetOf(typeof(GObject_g_type_instanceAlign), "g_type_instance")
@@ -947,7 +947,7 @@ namespace GLib {
 					),
 				new GLib.AbiField("ref_count"
 					, -1
-					, (uint) Marshal.SizeOf(typeof(uint)) // ref_count
+					, (uint) sizeof (uint) // ref_count
 					, "g_type_instance"
 					, "qdata"
 					, (long) Marshal.OffsetOf(typeof(GObject_ref_countAlign), "ref_count")
@@ -955,7 +955,7 @@ namespace GLib {
 					),
 				new GLib.AbiField("qdata"
 					, -1
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // qdata
+					, (uint) sizeof (IntPtr) // qdata
 					, "ref_count"
 					, null
 					, (long) Marshal.OffsetOf(typeof(GObject_qdataAlign), "qdata")
@@ -965,149 +965,149 @@ namespace GLib {
 		);
 		//
 		// Internal representation of the wrapped ABI structure.
-		static public AbiStruct class_abi = new AbiStruct(new List<AbiField> {
+		static public unsafe AbiStruct class_abi = new AbiStruct(new List<AbiField> {
 				new GLib.AbiField("type_class"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, null
 					, "construct_props"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("construct_props"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "type_class"
 					, "constructor_cb"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("constructor_cb"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "construct_props"
 					, "set_prop_cb"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("set_prop_cb"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "constructor_cb"
 					, "get_prop_cb"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("get_prop_cb"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "set_prop_cb"
 					, "dispose"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dispose"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "get_prop_cb"
 					, "finalize"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("finalize"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "dispose"
 					, "dispatch_properties_changed"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dispatch_properties_changed"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "finalize"
 					, "notify"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("notify"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "dispatch_properties_changed"
 					, "constructed"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("constructed"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "notify"
 					, "dummy1"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dummy1"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "constructed"
 					, "dummy2"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dummy2"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "dummy1"
 					, "dummy3"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dummy3"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "dummy2"
 					, "dummy4"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dummy3"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "dummy2"
 					, "dummy4"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dummy4"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "dummy3"
 					, "dummy5"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dummy5"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "dummy4"
 					, "dummy6"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dummy6"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "dummy5"
 					, "dummy7"
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 				new GLib.AbiField("dummy7"
 					, 0
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, "dummy6"
 					, null
-					, (uint) Marshal.SizeOf(typeof(IntPtr)) // g_type_instance
+					, (uint) sizeof (IntPtr) // g_type_instance
 					, 0
 					),
 			}
diff --git a/Source/Libs/GLibSharp/Signal.cs b/Source/Libs/GLibSharp/Signal.cs
index dd94e6c38..180b4d585 100644
--- a/Source/Libs/GLibSharp/Signal.cs
+++ b/Source/Libs/GLibSharp/Signal.cs
@@ -92,7 +92,7 @@ namespace GLib {
 			{
 				object[] pvals = new object [n_pvals];
 				for (int i = 0; i < n_pvals; i++) {
-					IntPtr p = new IntPtr ((long) pvals_ptr + i * Marshal.SizeOf (typeof (Value)));
+					IntPtr p = new IntPtr ((long) pvals_ptr + i * Marshal.SizeOf<Value> ());
 					Value v = (Value) Marshal.PtrToStructure (p, typeof (Value));
 					pvals [i] = v.Val;
 				}
@@ -110,7 +110,7 @@ namespace GLib {
 
 			bool NativeInvoker (InvocationHint ihint, object[] pvals)
 			{
-				int val_sz = Marshal.SizeOf (typeof (Value));
+				int val_sz = Marshal.SizeOf<Value> ();
 				IntPtr buf = Marshal.AllocHGlobal (pvals.Length * val_sz);
 				Value[] vals = new Value [pvals.Length];
 				for (int i = 0; i < pvals.Length; i++) {
diff --git a/Source/Libs/GLibSharp/SignalClosure.cs b/Source/Libs/GLibSharp/SignalClosure.cs
index 71c554195..7beee013d 100644
--- a/Source/Libs/GLibSharp/SignalClosure.cs
+++ b/Source/Libs/GLibSharp/SignalClosure.cs
@@ -72,7 +72,7 @@ namespace GLib {
 
 		public SignalClosure (IntPtr obj, string signal_name, System.Type args_type)
 		{
-			raw_closure = g_closure_new_simple (Marshal.SizeOf (typeof (GClosure)), IntPtr.Zero);
+			raw_closure = g_closure_new_simple (Marshal.SizeOf<GClosure> (), IntPtr.Zero);
 			g_closure_set_marshal (raw_closure, Marshaler);
 			g_closure_add_finalize_notifier (raw_closure, IntPtr.Zero, Notify);
 			closures [raw_closure] = this;
@@ -159,7 +159,7 @@ namespace GLib {
 				args.Args = new object [n_param_vals - 1];
 				GLib.Value[] vals = new GLib.Value [n_param_vals - 1];
 				for (int i = 1; i < n_param_vals; i++) {
-					IntPtr ptr = new IntPtr (param_values.ToInt64 () + i * Marshal.SizeOf (typeof (Value)));
+					IntPtr ptr = new IntPtr (param_values.ToInt64 () + i * Marshal.SizeOf<Value> ());
 					vals [i - 1] = (Value) Marshal.PtrToStructure (ptr, typeof (Value));
 					args.Args [i - 1] = vals [i - 1].Val;
 				}
@@ -167,7 +167,7 @@ namespace GLib {
 				closure.Invoke (ci_args);
 				for (int i = 1; i < n_param_vals; i++) {
 					vals [i - 1].Update (args.Args [i - 1]);
-					IntPtr ptr = new IntPtr (param_values.ToInt64 () + i * Marshal.SizeOf (typeof (Value)));
+					IntPtr ptr = new IntPtr (param_values.ToInt64 () + i * Marshal.SizeOf<Value> ());
 					Marshal.StructureToPtr (vals [i - 1], ptr, false);
 				}
 				if (return_val == IntPtr.Zero || args.RetVal == null)
diff --git a/Source/Libs/GLibSharp/TimeVal.cs b/Source/Libs/GLibSharp/TimeVal.cs
index da0a580cc..f1d6b983f 100644
--- a/Source/Libs/GLibSharp/TimeVal.cs
+++ b/Source/Libs/GLibSharp/TimeVal.cs
@@ -43,7 +43,7 @@ namespace GLib {
 		static d_g_time_val_add g_time_val_add = FuncLoader.LoadFunction<d_g_time_val_add>(FuncLoader.GetProcAddress(GLibrary.Load(Library.GLib), "g_time_val_add"));
 
 		public void Add(long microseconds) {
-			IntPtr this_as_native = System.Runtime.InteropServices.Marshal.AllocHGlobal (System.Runtime.InteropServices.Marshal.SizeOf (this));
+			IntPtr this_as_native = System.Runtime.InteropServices.Marshal.AllocHGlobal (System.Runtime.InteropServices.Marshal.SizeOf<TimeVal> ());
 			System.Runtime.InteropServices.Marshal.StructureToPtr (this, this_as_native, false);
 			g_time_val_add(this_as_native, new IntPtr (microseconds));
 			ReadNative (this_as_native, ref this);
@@ -54,7 +54,7 @@ namespace GLib {
 		static d_g_time_val_to_iso8601 g_time_val_to_iso8601 = FuncLoader.LoadFunction<d_g_time_val_to_iso8601>(FuncLoader.GetProcAddress(GLibrary.Load(Library.GLib), "g_time_val_to_iso8601"));
 
 		public string ToIso8601() {
-			IntPtr this_as_native = System.Runtime.InteropServices.Marshal.AllocHGlobal (System.Runtime.InteropServices.Marshal.SizeOf (this));
+			IntPtr this_as_native = System.Runtime.InteropServices.Marshal.AllocHGlobal (System.Runtime.InteropServices.Marshal.SizeOf<TimeVal> ());
 			System.Runtime.InteropServices.Marshal.StructureToPtr (this, this_as_native, false);
 			IntPtr raw_ret = g_time_val_to_iso8601(this_as_native);
 			string ret = GLib.Marshaller.PtrToStringGFree(raw_ret);
@@ -68,7 +68,7 @@ namespace GLib {
 
 		public static bool FromIso8601(string iso_date, out GLib.TimeVal time_) {
 			IntPtr native_iso_date = GLib.Marshaller.StringToPtrGStrdup (iso_date);
-			IntPtr native_time_ = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (GLib.TimeVal)));
+			IntPtr native_time_ = Marshal.AllocHGlobal (Marshal.SizeOf<GLib.TimeVal> ());
 			bool raw_ret = g_time_val_from_iso8601(native_iso_date, native_time_);
 			bool ret = raw_ret;
 			GLib.Marshaller.Free (native_iso_date);
diff --git a/Source/Libs/GdkSharp/Keymap.cs b/Source/Libs/GdkSharp/Keymap.cs
index ec7132798..e166f6240 100644
--- a/Source/Libs/GdkSharp/Keymap.cs
+++ b/Source/Libs/GdkSharp/Keymap.cs
@@ -39,7 +39,7 @@ namespace Gdk {
 				int[] tmp = new int [count];
 				Marshal.Copy (keyval_ptr, tmp, 0, count);
 				for (int i = 0; i < count; i++) {
-					IntPtr ptr = new IntPtr ((long) key_ptr + i * Marshal.SizeOf (typeof (KeymapKey)));
+					IntPtr ptr = new IntPtr ((long) key_ptr + i * Marshal.SizeOf<KeymapKey> ());
 					keyvals [i] = (uint) tmp [i];
 					keys [i] = KeymapKey.New (ptr);
 				}
@@ -61,7 +61,7 @@ namespace Gdk {
 			if (gdk_keymap_get_entries_for_keyval(Handle, keyval, out key_ptr, out count)) {
 				KeymapKey[] result = new KeymapKey [count];
 				for (int i = 0; i < count; i++) {
-					IntPtr ptr = new IntPtr ((long) key_ptr + i * Marshal.SizeOf (typeof (KeymapKey)));
+					IntPtr ptr = new IntPtr ((long) key_ptr + i * Marshal.SizeOf<KeymapKey> ());
 					result [i] = KeymapKey.New (ptr);
 				}
 				GLib.Marshaller.Free (key_ptr);
diff --git a/Source/Libs/GtkSharp/ColorSelection.cs b/Source/Libs/GtkSharp/ColorSelection.cs
index 7623dea5f..76bd71133 100644
--- a/Source/Libs/GtkSharp/ColorSelection.cs
+++ b/Source/Libs/GtkSharp/ColorSelection.cs
@@ -55,7 +55,7 @@ namespace Gtk {
 			for (int i=0; i < n_colors; i++)
 			{
 				colors[i] = Gdk.Color.New(parsedColors);
-				parsedColors = (IntPtr) ((int)parsedColors + Marshal.SizeOf(colors[i]));
+				parsedColors = (IntPtr) ((int)parsedColors + Marshal.SizeOf<Gdk.Color> ());
 			}
 			return colors;
 		}
diff --git a/Source/Libs/GtkSharp/ListStore.cs b/Source/Libs/GtkSharp/ListStore.cs
index 0870601c3..825ea0bf1 100644
--- a/Source/Libs/GtkSharp/ListStore.cs
+++ b/Source/Libs/GtkSharp/ListStore.cs
@@ -271,7 +271,7 @@ namespace Gtk {
 			vals [2] = new GLib.Value (iter);
 			inst_and_params.Append (vals [2]);
 			int cnt = IterNChildren ();
-			IntPtr new_order_ptr = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (int)) * cnt);
+			IntPtr new_order_ptr = Marshal.AllocHGlobal (sizeof(int) * cnt);
 			Marshal.Copy (new_order, 0, new_order_ptr, cnt);
 			vals [3] = new GLib.Value (new_order_ptr);
 			inst_and_params.Append (vals [3]);
diff --git a/Source/Libs/GtkSharp/StatusIcon.cs b/Source/Libs/GtkSharp/StatusIcon.cs
index f0d8989c9..116a9d467 100644
--- a/Source/Libs/GtkSharp/StatusIcon.cs
+++ b/Source/Libs/GtkSharp/StatusIcon.cs
@@ -90,7 +90,7 @@ namespace Gtk {
 		public bool GetGeometry(out Gdk.Screen screen, out Gdk.Rectangle area, out Gtk.Orientation orientation)
 		{
 			IntPtr native_screen;
-			IntPtr native_area = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (Gdk.Rectangle)));
+			IntPtr native_area = Marshal.AllocHGlobal (Marshal.SizeOf<Gdk.Rectangle> ());
 			int native_orientation;
 			bool ret = gtk_status_icon_get_geometry(Handle, out native_screen, native_area, out native_orientation);
 			if (ret) {
diff --git a/Source/Libs/GtkSharp/Target.cs b/Source/Libs/GtkSharp/Target.cs
index 6b5893564..b53935132 100644
--- a/Source/Libs/GtkSharp/Target.cs
+++ b/Source/Libs/GtkSharp/Target.cs
@@ -33,7 +33,7 @@ namespace Gtk {
 			IntPtr array_ptr = gtk_target_table_new_from_list (list.Handle, out n_targets);
 
 			Gtk.TargetEntry[] ret = new Gtk.TargetEntry [n_targets];
-			int unmanaged_struct_size = Marshal.SizeOf (typeof (Gtk.TargetEntry));
+			int unmanaged_struct_size = Marshal.SizeOf<Gtk.TargetEntry> ();
 			for (int i = 0; i < n_targets; i++) {
 				ret [i] = Gtk.TargetEntry.New (new IntPtr (array_ptr.ToInt64 () + i * unmanaged_struct_size));
 			}
diff --git a/Source/Libs/GtkSharp/TreeModelAdapter.cs b/Source/Libs/GtkSharp/TreeModelAdapter.cs
index ed0bc814f..4a0655654 100644
--- a/Source/Libs/GtkSharp/TreeModelAdapter.cs
+++ b/Source/Libs/GtkSharp/TreeModelAdapter.cs
@@ -161,7 +161,7 @@ namespace Gtk {
 			vals [2] = new GLib.Value (iter);
 			inst_and_params.Append (vals [2]);
 			int cnt = IterNChildren (iter);
-			IntPtr new_order_ptr = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (int)) * cnt);
+			IntPtr new_order_ptr = Marshal.AllocHGlobal (sizeof(int) * cnt);
 			Marshal.Copy (new_order, 0, new_order_ptr, cnt);
 			vals [3] = new GLib.Value (new_order_ptr);
 			inst_and_params.Append (vals [3]);
diff --git a/Source/Libs/GtkSharp/TreeModelFilter.cs b/Source/Libs/GtkSharp/TreeModelFilter.cs
index 4cb7ed67f..1ad1372e7 100644
--- a/Source/Libs/GtkSharp/TreeModelFilter.cs
+++ b/Source/Libs/GtkSharp/TreeModelFilter.cs
@@ -185,7 +185,7 @@ namespace Gtk {
 			vals [2] = new GLib.Value (iter);
 			inst_and_params.Append (vals [2]);
 			int cnt = IterNChildren (iter);
-			IntPtr new_order_ptr = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (int)) * cnt);
+			IntPtr new_order_ptr = Marshal.AllocHGlobal (sizeof(int) * cnt);
 			Marshal.Copy (new_order, 0, new_order_ptr, cnt);
 			vals [3] = new GLib.Value (new_order_ptr);
 			inst_and_params.Append (vals [3]);
diff --git a/Source/Libs/GtkSharp/TreeModelSort.cs b/Source/Libs/GtkSharp/TreeModelSort.cs
index 45fc3c572..2446bb21c 100644
--- a/Source/Libs/GtkSharp/TreeModelSort.cs
+++ b/Source/Libs/GtkSharp/TreeModelSort.cs
@@ -165,7 +165,7 @@ namespace Gtk {
 			vals [2] = new GLib.Value (iter);
 			inst_and_params.Append (vals [2]);
 			int cnt = IterNChildren (iter);
-			IntPtr new_order_ptr = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (int)) * cnt);
+			IntPtr new_order_ptr = Marshal.AllocHGlobal (sizeof(int) * cnt);
 			Marshal.Copy (new_order, 0, new_order_ptr, cnt);
 			vals [3] = new GLib.Value (new_order_ptr);
 			inst_and_params.Append (vals [3]);
diff --git a/Source/Libs/GtkSharp/TreeStore.cs b/Source/Libs/GtkSharp/TreeStore.cs
index 573128d2a..44c163c7c 100644
--- a/Source/Libs/GtkSharp/TreeStore.cs
+++ b/Source/Libs/GtkSharp/TreeStore.cs
@@ -382,7 +382,7 @@ namespace Gtk {
 			vals [2] = new GLib.Value (iter);
 			inst_and_params.Append (vals [2]);
 			int cnt = IterNChildren (iter);
-			IntPtr new_order_ptr = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (int)) * cnt);
+			IntPtr new_order_ptr = Marshal.AllocHGlobal (sizeof(int) * cnt);
 			Marshal.Copy (new_order, 0, new_order_ptr, cnt);
 			vals [3] = new GLib.Value (new_order_ptr);
 			inst_and_params.Append (vals [3]);
diff --git a/Source/Libs/GtkSharp/Widget.cs b/Source/Libs/GtkSharp/Widget.cs
index 78c74abd0..370f3ac18 100644
--- a/Source/Libs/GtkSharp/Widget.cs
+++ b/Source/Libs/GtkSharp/Widget.cs
@@ -65,7 +65,7 @@ namespace Gtk {
 		static d_g_closure_set_marshal g_closure_set_marshal = FuncLoader.LoadFunction<d_g_closure_set_marshal>(FuncLoader.GetProcAddress(GLibrary.Load(Library.GObject), "g_closure_set_marshal"));
 
 		static IntPtr CreateClosure (ClosureMarshal marshaler) {
-			IntPtr raw_closure = g_closure_new_simple (Marshal.SizeOf (typeof (GClosure)), IntPtr.Zero);
+			IntPtr raw_closure = g_closure_new_simple (Marshal.SizeOf<GClosure> (), IntPtr.Zero);
 			g_closure_set_marshal (raw_closure, marshaler);
 			return raw_closure;
 		}
@@ -149,7 +149,7 @@ namespace Gtk {
 		{
 			try {
 				GLib.Value[] inst_and_params = new GLib.Value [n_param_vals];
-				int gvalue_size = Marshal.SizeOf (typeof (GLib.Value));
+				int gvalue_size = Marshal.SizeOf<GLib.Value> ();
 				for (int idx = 0; idx < n_param_vals; idx++)
 					inst_and_params [idx] = (GLib.Value) Marshal.PtrToStructure (new IntPtr (param_values.ToInt64 () + idx * gvalue_size), typeof (GLib.Value));
 
diff --git a/Source/OldStuff/doc/en/GLib/Marshaller.xml b/Source/OldStuff/doc/en/GLib/Marshaller.xml
index dde9f77da..509bba1a8 100644
--- a/Source/OldStuff/doc/en/GLib/Marshaller.xml
+++ b/Source/OldStuff/doc/en/GLib/Marshaller.xml
@@ -508,7 +508,7 @@
       </Docs>
     </Member>
     <Member MemberName="StructArrayToNullTerminatedStructArrayIntPtr&lt;T&gt;">
-      <MemberSignature Language="C#" Value="public static IntPtr StructArrayToNullTerminatedStructArrayIntPtr&lt;T&gt; (T[] InputArray);" />
+      <MemberSignature Language="C#" Value="public static IntPtr unsafe StructArrayToNullTerminatedStructArrayIntPtr&lt;T&gt; (T[] InputArray);" />
       <MemberSignature Language="ILAsm" Value=".method public static hidebysig native int StructArrayToNullTerminatedStructArrayIntPtr&lt;T&gt;(!!T[] InputArray) cil managed" />
       <MemberType>Method</MemberType>
       <ReturnValue>
diff --git a/Source/Tools/GapiCodegen/ByRefGen.cs b/Source/Tools/GapiCodegen/ByRefGen.cs
index 232c3252b..70e3163fe 100644
--- a/Source/Tools/GapiCodegen/ByRefGen.cs
+++ b/Source/Tools/GapiCodegen/ByRefGen.cs
@@ -41,7 +41,7 @@ namespace GtkSharp.Generation {
 		
 		public string AllocNative ()
 		{
-			return "Marshal.AllocHGlobal (Marshal.SizeOf (typeof (" + QualifiedName + ")))";
+			return "Marshal.AllocHGlobal (" + GenerationInfo.GetSizeOfExpression(QualifiedName) + ")";
 		}
 
 		public string AllocNative (string var_name)
diff --git a/Source/Tools/GapiCodegen/ClassBase.cs b/Source/Tools/GapiCodegen/ClassBase.cs
index 0ff0bb58d..7a9704c69 100644
--- a/Source/Tools/GapiCodegen/ClassBase.cs
+++ b/Source/Tools/GapiCodegen/ClassBase.cs
@@ -227,7 +227,7 @@ namespace GtkSharp.Generation {
 			sw.WriteLine ();
 			sw.WriteLine ("\t\t// Internal representation of the wrapped structure ABI.");
 			sw.WriteLine ("\t\tstatic GLib.AbiStruct _" + info_name + " = null;");
-			sw.WriteLine ("\t\tstatic public " + _new + "GLib.AbiStruct " + info_name + " {");
+			sw.WriteLine ("\t\tstatic public unsafe " + _new + "GLib.AbiStruct " + info_name + " {");
 			sw.WriteLine ("\t\t\tget {");
 			sw.WriteLine ("\t\t\t\tif (_" + info_name + " == null)");
 
diff --git a/Source/Tools/GapiCodegen/DefaultSignalHandler.cs b/Source/Tools/GapiCodegen/DefaultSignalHandler.cs
index 989310808..0dc83066e 100644
--- a/Source/Tools/GapiCodegen/DefaultSignalHandler.cs
+++ b/Source/Tools/GapiCodegen/DefaultSignalHandler.cs
@@ -90,7 +90,7 @@ namespace GtkSharp.Generation {
 						if (p.PassAs == "ref")
 							sw.WriteLine ("\t\t\tIntPtr " + p.Name + "_ptr = GLib.Marshaller.StructureToPtrAlloc (" + p.Generatable.CallByName (p.Name) + ");");
 						else
-							sw.WriteLine ("\t\t\tIntPtr " + p.Name + "_ptr = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (" + p.MarshalType + ")));");
+							sw.WriteLine ("\t\t\tIntPtr " + p.Name + "_ptr = Marshal.AllocHGlobal (" + GenerationInfo.GetSizeOfExpression(p.MarshalType) + ");");
 
 						sw.WriteLine ("\t\t\tvals [" + (i + 1) + "] = new GLib.Value (" + p.Name + "_ptr);");
 						cleanup += "\t\t\t" + p.Name + " = " + p.FromNative ("(" + p.MarshalType + ") Marshal.PtrToStructure (" + p.Name + "_ptr, typeof (" + p.MarshalType + "))") + ";\n";
diff --git a/Source/Tools/GapiCodegen/GenerationInfo.cs b/Source/Tools/GapiCodegen/GenerationInfo.cs
index 3472aff2e..6ef86b008 100644
--- a/Source/Tools/GapiCodegen/GenerationInfo.cs
+++ b/Source/Tools/GapiCodegen/GenerationInfo.cs
@@ -234,6 +234,27 @@ namespace GtkSharp.Generation {
 
 			return sw;
 		}
+
+		internal static string GetSizeOfExpression(string cstype)
+		{
+			// See https://docs.microsoft.com/en-us/dotnet/framework/interop/blittable-and-non-blittable-types
+			bool isBlittable = cstype == "IntPtr"
+				|| cstype == "UIntPtr"
+				|| cstype == "ulong"
+				|| cstype == "long"
+				|| cstype == "uint"
+				|| cstype == "int"
+				|| cstype == "ushort"
+				|| cstype == "short"
+				|| cstype == "byte"
+				|| cstype == "sbyte"
+				|| cstype == "float"
+				|| cstype == "double";
+			if (isBlittable)
+				return "sizeof( " + cstype + " )";
+
+			return "Marshal.SizeOf<" + cstype + ">()";
+		}
 	}
 }
 
diff --git a/Source/Tools/GapiCodegen/ManualGen.cs b/Source/Tools/GapiCodegen/ManualGen.cs
index 78a67b67f..fcc7aa801 100644
--- a/Source/Tools/GapiCodegen/ManualGen.cs
+++ b/Source/Tools/GapiCodegen/ManualGen.cs
@@ -68,7 +68,7 @@ namespace GtkSharp.Generation {
 		}
 
 		public override string GenerateGetSizeOf () {
-			return "(uint) Marshal.SizeOf(typeof(" + abi_type + "))";
+			return "(uint) " + GenerationInfo.GetSizeOfExpression(abi_type);
 		}
 	}
 }
diff --git a/Source/Tools/GapiCodegen/Parameter.cs b/Source/Tools/GapiCodegen/Parameter.cs
index a77db28fc..33fa9dfc7 100644
--- a/Source/Tools/GapiCodegen/Parameter.cs
+++ b/Source/Tools/GapiCodegen/Parameter.cs
@@ -394,7 +394,7 @@ namespace GtkSharp.Generation {
 		public override string[] Prepare {
 			get {
 				if (PassAs == "out")
-					return new string [] { "IntPtr native_" + CallName + " = Marshal.AllocHGlobal (Marshal.SizeOf (typeof (" + Generatable.QualifiedName + ")));"};
+					return new string [] { "IntPtr native_" + CallName + " = Marshal.AllocHGlobal (" + GenerationInfo.GetSizeOfExpression(Generatable.QualifiedName) + ");"};
 				else
 					return new string [] { "IntPtr native_" + CallName + " = " + (Generatable as IManualMarshaler).AllocNative (CallName) + ";"};
 			}
diff --git a/Source/Tools/GapiCodegen/StructABIField.cs b/Source/Tools/GapiCodegen/StructABIField.cs
index 90c3104ae..61f4f8965 100644
--- a/Source/Tools/GapiCodegen/StructABIField.cs
+++ b/Source/Tools/GapiCodegen/StructABIField.cs
@@ -104,7 +104,7 @@ namespace GtkSharp.Generation {
 
 				// Do not generate structs if the type is a simple pointer.
 				if (IsCPointer())
-					min_align = "(uint) Marshal.SizeOf(typeof(IntPtr))";
+					min_align = "(uint) sizeof(IntPtr)";
 
 				if (IsBitfield)
 					min_align = "1";
diff --git a/Source/Tools/GapiCodegen/StructBase.cs b/Source/Tools/GapiCodegen/StructBase.cs
index ad1c6b917..b3cf53431 100644
--- a/Source/Tools/GapiCodegen/StructBase.cs
+++ b/Source/Tools/GapiCodegen/StructBase.cs
@@ -298,7 +298,7 @@ namespace GtkSharp.Generation {
 
 		public override void Prepare (StreamWriter sw, string indent)
 		{
-			sw.WriteLine (indent + "IntPtr this_as_native = System.Runtime.InteropServices.Marshal.AllocHGlobal (System.Runtime.InteropServices.Marshal.SizeOf (this));");
+			sw.WriteLine (indent + "IntPtr this_as_native = System.Runtime.InteropServices.Marshal.AllocHGlobal (System.Runtime.InteropServices.Marshal.SizeOf<" + QualifiedName + ">());");
 			sw.WriteLine (indent + "System.Runtime.InteropServices.Marshal.StructureToPtr (this, this_as_native, false);");
 		}
 
diff --git a/Source/Tools/GapiCodegen/StructField.cs b/Source/Tools/GapiCodegen/StructField.cs
index 9503f5ed4..9b1b10428 100644
--- a/Source/Tools/GapiCodegen/StructField.cs
+++ b/Source/Tools/GapiCodegen/StructField.cs
@@ -142,9 +142,9 @@ namespace GtkSharp.Generation {
 
 			var _enum = gen as EnumGen;
 			if (_enum != null && !is_pointer)
-				res = "(uint) Marshal.SizeOf(System.Enum.GetUnderlyingType(typeof(" + cstype + ")))";
+				res = "(uint) sizeof(" + cstype + ")";
 			else
-				res = "(uint) Marshal.SizeOf(typeof(" + cstype + "))";
+				res = "(uint) " + GenerationInfo.GetSizeOfExpression(cstype);
 
 			if (IsFixedSizeArray())
 				res += " * " + ArrayLength;
diff --git a/Source/Tools/GapiCodegen/SymbolTable.cs b/Source/Tools/GapiCodegen/SymbolTable.cs
index 0e1cdc92d..922fb2152 100644
--- a/Source/Tools/GapiCodegen/SymbolTable.cs
+++ b/Source/Tools/GapiCodegen/SymbolTable.cs
@@ -150,7 +150,7 @@ namespace GtkSharp.Generation {
 			AddType (new MarshalGen ("GType", "GLib.GType", "IntPtr", "{0}.Val", "new GLib.GType({0})", "GLib.GType.None"));
 			AddType (new ByRefGen ("GValue", "GLib.Value"));
 			AddType (new SimpleGen ("GDestroyNotify", "GLib.DestroyNotify", "null",
-						"(uint) Marshal.SizeOf(typeof(IntPtr))"));
+						"(uint) sizeof(IntPtr)"));
 			AddType (new SimpleGen ("GThread", "GLib.Thread", "null"));
 			AddType (new ManualGen ("GBytes", "GLib.Bytes"));
 			AddType (new SimpleGen ("GHookList", "GLib.HookList", "null",