diff --git a/reactos/include/ascii.h b/reactos/include/ascii.h
index 0307bec6112..be57851bc91 100644
--- a/reactos/include/ascii.h
+++ b/reactos/include/ascii.h
@@ -2135,7 +2135,7 @@ FindNextFileA(
 WINBOOL
 STDCALL
 GetVersionExA(
-    LPOSVERSIONINFO lpVersionInformation
+    LPOSVERSIONINFOA lpVersionInformation
     );
 
 #define CreateWindowA(lpClassName, lpWindowName, dwStyle, x, y,\
diff --git a/reactos/include/napi/teb.h b/reactos/include/napi/teb.h
index 63ff5aa09ed..b570639f5aa 100644
--- a/reactos/include/napi/teb.h
+++ b/reactos/include/napi/teb.h
@@ -145,7 +145,9 @@ typedef struct _PEB
    PVOID LoaderLock;                                // A0h
    ULONG OSMajorVersion;                            // A4h
    ULONG OSMinorVersion;                            // A8h
-   ULONG OSBuildNumber;                             // ACh
+   USHORT OSBuildNumber;                            // ACh
+   UCHAR SPMajorVersion;                            // AEh
+   UCHAR SPMinorVersion;                            // AFh
    ULONG OSPlatformId;                              // B0h
    ULONG ImageSubSystem;                            // B4h
    ULONG ImageSubSystemMajorVersion;                // B8h
diff --git a/reactos/include/structs.h b/reactos/include/structs.h
index 95732e79aa2..22f7af1ea49 100644
--- a/reactos/include/structs.h
+++ b/reactos/include/structs.h
@@ -2898,14 +2898,65 @@ typedef struct _OFNOTIFY {
   LPTSTR         pszFile;
 } OFNOTIFY, *LPOFNOTIFY;
 
-typedef struct _OSVERSIONINFO {
+typedef struct _OSVERSIONINFOA {
   DWORD dwOSVersionInfoSize;
   DWORD dwMajorVersion;
   DWORD dwMinorVersion;
   DWORD dwBuildNumber;
   DWORD dwPlatformId;
-  TCHAR szCSDVersion[ 128 ];
-} OSVERSIONINFO, *POSVERSIONINFO, *LPOSVERSIONINFO;
+  CHAR szCSDVersion[ 128 ];
+} OSVERSIONINFOA, *POSVERSIONINFOA, *LPOSVERSIONINFOA;
+
+typedef struct _OSVERSIONINFOW {
+  DWORD dwOSVersionInfoSize;
+  DWORD dwMajorVersion;
+  DWORD dwMinorVersion;
+  DWORD dwBuildNumber;
+  DWORD dwPlatformId;
+  WCHAR szCSDVersion[ 128 ];
+} OSVERSIONINFOW, *POSVERSIONINFOW, *LPOSVERSIONINFOW;
+
+#ifdef UNICODE
+typedef OSVERSIONINFOA OSVERSIONINFO;
+#else
+typedef OSVERSIONINFOW OSVERSIONINFO;
+#endif
+
+typedef struct _OSVERSIONINFOEXA
+#ifdef __cplusplus
+: public OSVERSIONINFOA
+{
+#else
+{
+ OSVERSIONINFOA;
+#endif
+ WORD wServicePackMajor;
+ WORD wServicePackMinor;
+ WORD wSuiteMask;
+ BYTE wProductType;
+ BYTE wReserved;
+} OSVERSIONINFOEXA, *POSVERSIONINFOEXA, *LPOSVERSIONINFOEXA;
+
+typedef struct _OSVERSIONINFOEXW
+#ifdef __cplusplus
+: public OSVERSIONINFOW
+{
+#else
+{
+ OSVERSIONINFOW;
+#endif
+ WORD wServicePackMajor;
+ WORD wServicePackMinor;
+ WORD wSuiteMask;
+ BYTE wProductType;
+ BYTE wReserved;
+} OSVERSIONINFOEXW, *POSVERSIONINFOEXW, *LPOSVERSIONINFOEXW;
+
+#ifdef UNICODE
+typedef OSVERSIONINFOEXA OSVERSIONINFOEX;
+#else
+typedef OSVERSIONINFOEXW OSVERSIONINFOEX;
+#endif
 
 typedef struct tagTEXTMETRIC {
   LONG tmHeight;
diff --git a/reactos/include/unicode.h b/reactos/include/unicode.h
index 881811c52d2..dcf22bb23d5 100644
--- a/reactos/include/unicode.h
+++ b/reactos/include/unicode.h
@@ -2152,7 +2152,7 @@ FindNextFileW(
 WINBOOL
 STDCALL
 GetVersionExW(
-    LPOSVERSIONINFO lpVersionInformation
+    LPOSVERSIONINFOW lpVersionInformation
     );
 
 #define CreateWindowW(lpClassName, lpWindowName, dwStyle, x, y,\