--- a/gambas/trunk/main/share/gambas.h
+++ b/gambas/trunk/main/share/gambas.h
@@ -66,7 +66,8 @@
 #endif
 
 #if defined(__cplusplus) && !defined(__clang__)
-	#define __null ((intptr_t)0)
+	#undef NULL
+	#define NULL ((intptr_t)0)
 #else
 	#ifdef bool
 		#undef bool
--- a/gambas/trunk/gb.sdl/src/Cmouse.cpp
+++ b/gambas/trunk/gb.sdl/src/Cmouse.cpp
@@ -35,7 +35,7 @@
 CMOUSE_INFO CMOUSE_info = { 0 };
 
 #define CHECK_VALID() \
-  if (UNLIKELY(CMOUSE_info.valid ==  NULL)) \
+  if (UNLIKELY(!CMOUSE_info.valid)) \
   { \
     GB.Error("No mouse event data"); \
     return; \
--- a/gambas/trunk/gb.sdl/src/Cjoystick.cpp
+++ b/gambas/trunk/gb.sdl/src/Cjoystick.cpp
@@ -46,7 +46,7 @@
 CJOY_INFO CJOY_info = { 0 };
 
 #define CHECK_VALID() \
-  if (UNLIKELY(CJOY_info.valid == NULL)) \
+  if (UNLIKELY(!CJOY_info.valid)) \
   { \
     GB.Error("No joystick event data"); \
     return; \
--- a/gambas/trunk/gb.qt4/src/CWidget.cpp
+++ b/gambas/trunk/gb.qt4/src/CWidget.cpp
@@ -2297,7 +2297,7 @@
 		{
 			_post_check_hovered = true;
 			_post_check_hovered_window = top;
-			GB.Post((void (*)())post_check_hovered, NULL);
+			GB.Post((void (*)())post_check_hovered, (intptr_t)NULL);
 		}
 	}
 	
@@ -2392,7 +2392,7 @@
 		return;
 	
 	_focus_change = TRUE;
-	GB.Post((void (*)())post_focus_change, NULL);
+	GB.Post((void (*)())post_focus_change, (intptr_t)NULL);
 }
 
 void CWIDGET_finish_focus(void)
--- a/gambas/trunk/gb.qt4/src/CImage.cpp
+++ b/gambas/trunk/gb.qt4/src/CImage.cpp
@@ -126,7 +126,7 @@
 CIMAGE *CIMAGE_create(QImage *image)
 {
 	CIMAGE *img;
-	static GB_CLASS class_id = NULL;
+	static GB_CLASS class_id = 0;
 
 	if (!class_id)
 		class_id = GB.FindClass("Image");
--- a/gambas/trunk/gb.gtk/src/CImage.cpp
+++ b/gambas/trunk/gb.gtk/src/CImage.cpp
@@ -79,7 +79,7 @@
 CIMAGE *CIMAGE_create(gPicture *image)
 {
 	CIMAGE *img;
-  static GB_CLASS class_id = NULL;
+  static GB_CLASS class_id = 0;
 
   if (!class_id)
     class_id = GB.FindClass("Image");