diff --git a/reactos/tools/widl/typelib.c b/reactos/tools/widl/typelib.c
index 9c24f152629..ce099c8d0f2 100644
--- a/reactos/tools/widl/typelib.c
+++ b/reactos/tools/widl/typelib.c
@@ -35,8 +35,7 @@
 #define NONAMELESSUNION
 #define NONAMELESSSTRUCT
 
-#include "windef.h"
-#include "winbase.h"
+#include <host/typedefs.h>
 
 #include "widl.h"
 #include "utils.h"
diff --git a/reactos/tools/widl/typelib_struct.h b/reactos/tools/widl/typelib_struct.h
index 79b86b91216..01c2c642a81 100644
--- a/reactos/tools/widl/typelib_struct.h
+++ b/reactos/tools/widl/typelib_struct.h
@@ -302,7 +302,7 @@ typedef struct {
  *
  */
 
-#include "pshpack1.h"
+#include <host/pshpack1.h>
 
 typedef struct {
 /*00*/	DWORD SLTG_magic;	/* 0x47544c53  == "SLTG" */
@@ -599,7 +599,7 @@ WORD offset from start of block to SAFEARRAY
 WORD typeofarray
 */
 
-#include "poppack.h"
+#include <host/poppack.h>
 
 /*---------------------------END--------------------------------------------*/
 #endif
diff --git a/reactos/tools/widl/widltypes.h b/reactos/tools/widl/widltypes.h
index 79175082732..74f31052143 100644
--- a/reactos/tools/widl/widltypes.h
+++ b/reactos/tools/widl/widltypes.h
@@ -21,6 +21,13 @@
 #ifndef __WIDL_WIDLTYPES_H
 #define __WIDL_WIDLTYPES_H
 
+#define S_OK           0 	 
+#define S_FALSE        1 	 
+#define E_OUTOFMEMORY  ((HRESULT)0x8007000EL) 	 
+#define TYPE_E_IOERROR ((HRESULT)0x80028CA2L)
+
+#define max(a, b) ((a) > (b) ? a : b)
+
 #include <stdarg.h>
 #include <assert.h>
 #include "guiddef.h"
diff --git a/reactos/tools/widl/write_msft.c b/reactos/tools/widl/write_msft.c
index 1ac34d0a9b1..b60c8f38646 100644
--- a/reactos/tools/widl/write_msft.c
+++ b/reactos/tools/widl/write_msft.c
@@ -40,10 +40,8 @@
 #define NONAMELESSUNION
 #define NONAMELESSSTRUCT
 
-#include "winerror.h"
-#include "windef.h"
-#include "winbase.h"
-#include "winnls.h"
+#include <host/typedefs.h>
+#include <host/nls.h>
 
 #include "widl.h"
 #include "typelib.h"