diff --git a/SDK/INC/NT/guiddef.h b/SDK/INC/NT/guiddef.h
new file mode 100644
index 0000000..01e8b99
--- /dev/null
+++ b/SDK/INC/NT/guiddef.h
@@ -0,0 +1,29 @@
+/*++
+
+Copyright (c) 2024, Quinn Stephens.
+Provided under the BSD 3-Clause license.
+
+Module Name:
+
+   guiddef.h
+
+Abstract:
+
+   Provides GUID definitions.
+
+--*/
+
+#ifndef _GUIDDEF_H
+#define _GUIDDEF_H
+
+#ifndef GUID_DEFINED
+#define GUID_DEFINED
+typedef struct _GUID {
+    ULONG Data1;
+    USHORT Data2;
+    USHORT Data3;
+    UCHAR Data4[8];
+} GUID;
+#endif
+
+#endif /* !_GUIDDEF_H */
diff --git a/SDK/INC/NT/ntdef.h b/SDK/INC/NT/ntdef.h
index d0d1abe..602caac 100644
--- a/SDK/INC/NT/ntdef.h
+++ b/SDK/INC/NT/ntdef.h
@@ -30,14 +30,6 @@ Abstract:
 #define OPTIONAL
 #endif
 
-#ifndef FASTCALL
-#define FASTCALL
-#endif
-
-#ifndef NTAPI
-#define NTAPI
-#endif
-
 #ifndef VOID
 #define VOID void
 #endif
@@ -50,19 +42,35 @@ Abstract:
 #define ANYSIZE_ARRAY 1
 #endif
 
+#ifndef NULL
+#if defined(__cplusplus)
+#define NULL 0
+#else
+#define NULL ((VOID *)0)
+#endif
+#endif
+
 #ifndef FORCEINLINE
 #if defined(_MSC_EXTENSIONS)
-#define FORCEINLINE __inline
+#define FORCEINLINE __forceinline
 #else
 #define FORCEINLINE static inline
 #endif
 #endif
 
-#ifndef NULL
-#ifdef __cplusplus
-#define NULL 0
+#ifndef FASTCALL
+#if defined(_M_IX86)
+#define FASTCALL __fastcall
 #else
-#define NULL ((VOID *)0)
+#define FASTCALL
+#endif
+#endif
+
+#ifndef NTAPI
+#if !defined(_M_AMD64)
+#define NTAPI __stdcall
+#else
+#define NTAPI
 #endif
 #endif
 
@@ -76,6 +84,19 @@ typedef unsigned char UCHAR;
 typedef unsigned short USHORT;
 typedef unsigned long ULONG;
 
+//
+// Minimum/maximum values of basic types.
+//
+#define MINCHAR   0x80
+#define MAXCHAR   0x7f
+#define MINSHORT  0x8000
+#define MAXSHORT  0x7fff
+#define MINLONG   0x80000000
+#define MAXLONG   0x7fffffff
+#define MAXUCHAR  0xff
+#define MAXUSHORT 0xffff
+#define MAXULONG  0xffffffff
+
 //
 // Basic pointer types.
 //
@@ -86,27 +107,51 @@ typedef UCHAR *PUCHAR;
 typedef USHORT *PUSHORT;
 typedef ULONG *PULONG;
 
-//
-// Logical value types.
-//
-typedef ULONG LOGICAL;
-typedef ULONG *PLOGICAL;
-
 //
 // String types.
 //
-typedef CHAR *LPSTR;
-typedef CONST CHAR *LPCSTR;
+typedef CHAR *PSTR, *LPSTR;
+typedef CONST CHAR *PCSTR, *LPCSTR;
 
 //
 // Wide character/string types.
 //
 typedef USHORT WCHAR;
-typedef WCHAR *PWCHAR, *LPWSTR;
-typedef CONST WCHAR *LPCWSTR;
+typedef WCHAR *PWCHAR, *PWSTR, *LPWSTR;
+typedef CONST WCHAR *PCWSTR, *LPCWSTR;
 
 //
-// Status codes.
+// Long long types.
+//
+#if defined(_MSC_EXTENSIONS)
+typedef __int64 LONGLONG;
+typedef unsigned __int64 ULONGLONG;
+#elif defined(UNIX_LP64)
+typedef long LONGLONG;
+typedef unsigned long ULONGLONG;
+#else
+typedef long long LONGLONG;
+typedef unsigned long long ULONGLONG;
+#endif
+
+typedef LONGLONG *PLONGLONG;
+typedef ULONGLONG *PULONGLONG;
+
+#define MAXLONGLONG  (0x7fffffffffffffff)
+
+//
+// Logical/boolean value types.
+//
+typedef ULONG LOGICAL;
+typedef ULONG *PLOGICAL;
+typedef UCHAR BOOLEAN;
+typedef BOOLEAN *PBOOLEAN;
+
+#define TRUE  1
+#define FALSE 0
+
+//
+// Status code types.
 //
 typedef LONG NTSTATUS;
 typedef NTSTATUS *PNTSTATUS;
@@ -120,19 +165,20 @@ typedef NTSTATUS *PNTSTATUS;
 #define NT_ERROR(Status)       ((ULONG)(Status) >> 30 == 3)
 
 //
-// Long long type definitions.
+// Struct field offset helper.
 //
-#if defined(_MSC_EXTENSIONS)
-typedef unsigned __int64 ULONGLONG;
-typedef __int64 LONGLONG;
-#elif defined(UNIX_LP64)
-typedef unsigned long ULONGLONG;
-typedef long LONGLONG;
+#if defined(__clang__) || defined(__GNUC__)
+#define FIELD_OFFSET(type, field) ((ULONG)__builtin_offsetof(type, field))
 #else
-typedef unsigned long long ULONGLONG;
-typedef long long LONGLONG;
+#define FIELD_OFFSET(type, field) ((ULONG)&(((type *)0)->field))
 #endif
 
+//
+// Alignment helpers.
+//
+#define ALIGN_DOWN(x, a) ((x) & ~((a) - 1))
+#define ALIGN_UP(x, a)   ALIGN_DOWN((x) + (a) - 1, a)
+
 //
 // Large (64-bit) integer value.
 //
@@ -157,21 +203,6 @@ typedef union ULARGE_INTEGER {
     ULONGLONG QuadPart;
 } ULARGE_INTEGER, *PULARGE_INTEGER;
 
-//
-// Struct field offset helper.
-//
-#if !defined(__GNUC__) && !defined(__clang__)
-#define FIELD_OFFSET(type, field) ((ULONG)&(((type *)0)->field))
-#else
-#define FIELD_OFFSET(type, field) ((ULONG)__builtin_offsetof(type, field))
-#endif
-
-//
-// Alignment helpers.
-//
-#define ALIGN_DOWN(x, a) ((x) & ~((a) - 1))
-#define ALIGN_UP(x, a)   ALIGN_DOWN((x) + (a) - 1, a)
-
 //
 // Doubly-linked list entry.
 //
@@ -180,4 +211,20 @@ typedef struct _LIST_ENTRY {
     struct _LIST_ENTRY *BackLink;
 } LIST_ENTRY, *PLIST_ENTRY;
 
+//
+// Unicode string.
+//
+typedef struct _UNICODE_STRING {
+    USHORT Length;
+    USHORT MaximumLength;
+    PWSTR Buffer;
+} UNICODE_STRING, *PUNICODE_STRING;
+typedef CONST UNICODE_STRING *PCUNICODE_STRING;
+
+#define UNICODE_NULL ((WCHAR) 0)
+
+#define MAX_USTRING ALIGN_DOWN(MAXUSHORT, sizeof(WCHAR))
+
+#include <guiddef.h>
+
 #endif /* !_NTDEF_H */