diff --git a/include/crt/crtdefs.h b/include/crt/crtdefs.h
index c941eae87a2..8ff8d0d3764 100644
--- a/include/crt/crtdefs.h
+++ b/include/crt/crtdefs.h
@@ -245,7 +245,7 @@ extern "C" {
 #if defined(__GNUC__) && defined(__STRICT_ANSI__)
   typedef unsigned int size_t __attribute__ ((mode (DI)));
 #else
-  typedef unsigned __int64 size_t;
+  __MINGW_EXTENSION typedef unsigned __int64 size_t;
 #endif
 #else
   typedef unsigned int size_t;
@@ -261,7 +261,7 @@ extern "C" {
 #if defined(__GNUC__) && defined(__STRICT_ANSI__)
   typedef int intptr_t __attribute__ ((mode (DI)));
 #else
-  typedef __int64 intptr_t;
+  __MINGW_EXTENSION typedef __int64 intptr_t;
 #endif
 #else
   typedef int intptr_t;
@@ -278,7 +278,7 @@ extern "C" {
 #if defined(__GNUC__) && defined(__STRICT_ANSI__)
   typedef unsigned int uintptr_t __attribute__ ((mode (DI)));
 #else
-  typedef unsigned __int64 uintptr_t;
+  __MINGW_EXTENSION typedef unsigned __int64 uintptr_t;
 #endif
 #else
   typedef unsigned int uintptr_t;
@@ -294,7 +294,7 @@ extern "C" {
 #if defined(__GNUC__) && defined(__STRICT_ANSI__)
   typedef int ptrdiff_t __attribute__ ((mode (DI)));
 #else
-  typedef __int64 ptrdiff_t;
+  __MINGW_EXTENSION typedef __int64 ptrdiff_t;
 #endif
 #else
   typedef int ptrdiff_t;
@@ -329,7 +329,7 @@ extern "C" {
 #ifndef _TIME64_T_DEFINED
 #define _TIME64_T_DEFINED
 #if _INTEGRAL_MAX_BITS >= 64
-  typedef __int64 __time64_t;
+  __MINGW_EXTENSION typedef __int64 __time64_t;
 #endif
 #endif
 
diff --git a/include/crt/excpt.h b/include/crt/excpt.h
index 8a7badba888..d0d3ef077de 100644
--- a/include/crt/excpt.h
+++ b/include/crt/excpt.h
@@ -34,7 +34,7 @@ typedef enum _EXCEPTION_DISPOSITION
   struct _CONTEXT;
   struct _DISPATCHER_CONTEXT;
 
-  _CRTIMP EXCEPTION_DISPOSITION __cdecl __C_specific_handler (struct _EXCEPTION_RECORD *_ExceptionRecord,unsigned __int64 _MemoryStackFp,unsigned __int64 _BackingStoreFp,struct _CONTEXT *_ContextRecord,struct _DISPATCHER_CONTEXT *_DispatcherContext,unsigned __int64 _GlobalPointer);
+  __MINGW_EXTENSION _CRTIMP EXCEPTION_DISPOSITION __cdecl __C_specific_handler (struct _EXCEPTION_RECORD *_ExceptionRecord,unsigned __int64 _MemoryStackFp,unsigned __int64 _BackingStoreFp,struct _CONTEXT *_ContextRecord,struct _DISPATCHER_CONTEXT *_DispatcherContext,unsigned __int64 _GlobalPointer);
 #elif defined(__x86_64)
 
   struct _EXCEPTION_RECORD;
diff --git a/include/crt/fpieee.h b/include/crt/fpieee.h
index 74afa77d258..3fd5d539c38 100644
--- a/include/crt/fpieee.h
+++ b/include/crt/fpieee.h
@@ -49,7 +49,7 @@ extern "C" {
   typedef int _I32;
   typedef unsigned short _U16;
   typedef unsigned int _U32;
-  typedef __int64 _Q64;
+  __MINGW_EXTENSION typedef __int64 _Q64;
 
   typedef struct
 #if defined(__ia64__)
diff --git a/include/crt/io.h b/include/crt/io.h
index 2eaae8f4581..4a3f37dafbb 100644
--- a/include/crt/io.h
+++ b/include/crt/io.h
@@ -51,7 +51,7 @@ _CRTIMP char* __cdecl _getcwd (char*, int);
     time_t time_create;
     time_t time_access;
     time_t time_write;
-    __int64 size;
+    __MINGW_EXTENSION __int64 size;
     char name[260];
   };
 
@@ -60,7 +60,7 @@ _CRTIMP char* __cdecl _getcwd (char*, int);
     __time32_t time_create;
     __time32_t time_access;
     __time32_t time_write;
-    __int64 size;
+    __MINGW_EXTENSION __int64 size;
     char name[260];
   };
 
@@ -78,7 +78,7 @@ _CRTIMP char* __cdecl _getcwd (char*, int);
     __time64_t time_create;
     __time64_t time_access;
     __time64_t time_write;
-    __int64 size;
+    __MINGW_EXTENSION __int64 size;
     char name[260];
   };
 #endif /* _INTEGRAL_MAX_BITS >= 64 */
@@ -113,7 +113,7 @@ _CRTIMP char* __cdecl _getcwd (char*, int);
     time_t time_create;
     time_t time_access;
     time_t time_write;
-    __int64 size;
+    __MINGW_EXTENSION __int64 size;
     wchar_t name[260];
   };
 
@@ -122,7 +122,7 @@ _CRTIMP char* __cdecl _getcwd (char*, int);
     __time32_t time_create;
     __time32_t time_access;
     __time32_t time_write;
-    __int64 size;
+    __MINGW_EXTENSION __int64 size;
     wchar_t name[260];
   };
 
@@ -140,7 +140,7 @@ _CRTIMP char* __cdecl _getcwd (char*, int);
     __time64_t time_create;
     __time64_t time_access;
     __time64_t time_write;
-    __int64 size;
+    __MINGW_EXTENSION __int64 size;
     wchar_t name[260];
   };
 #endif
@@ -200,15 +200,15 @@ _CRTIMP char* __cdecl _getcwd (char*, int);
   _CRTIMP int __cdecl _write(int _FileHandle,const void *_Buf,unsigned int _MaxCharCount);
 
 #if _INTEGRAL_MAX_BITS >= 64
-  _CRTIMP __int64 __cdecl _filelengthi64(int _FileHandle);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _filelengthi64(int _FileHandle);
   _CRTIMP intptr_t __cdecl _findfirst32i64(const char *_Filename,struct _finddata32i64_t *_FindData);
   _CRTIMP intptr_t __cdecl _findfirst64i32(const char *_Filename,struct _finddata64i32_t *_FindData);
   _CRTIMP intptr_t __cdecl _findfirst64(const char *_Filename,struct __finddata64_t *_FindData);
   _CRTIMP int __cdecl _findnext32i64(intptr_t _FindHandle,struct _finddata32i64_t *_FindData);
   _CRTIMP int __cdecl _findnext64i32(intptr_t _FindHandle,struct _finddata64i32_t *_FindData);
   _CRTIMP int __cdecl _findnext64(intptr_t _FindHandle,struct __finddata64_t *_FindData);
-  _CRTIMP __int64 __cdecl _lseeki64(int _FileHandle,__int64 _Offset,int _Origin);
-  _CRTIMP __int64 __cdecl _telli64(int _FileHandle);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _lseeki64(int _FileHandle,__int64 _Offset,int _Origin);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _telli64(int _FileHandle);
 #ifdef __cplusplus
 #include <string.h>
 #endif
diff --git a/include/crt/math.h b/include/crt/math.h
index 159d048c0ae..9b645c15a51 100644
--- a/include/crt/math.h
+++ b/include/crt/math.h
@@ -584,23 +584,23 @@ __CRT_INLINE int isinf (double d) {
     return retval;
   }
 
-  __CRT_INLINE long long __cdecl llrint (double x)
+  __MINGW_EXTENSION __CRT_INLINE long long __cdecl llrint (double x)
   {
-    long long retval;
+    __MINGW_EXTENSION long long retval;
     __fistpll(x, retval);
     return retval;
   }
 
-  __CRT_INLINE long long __cdecl llrintf (float x)
+  __MINGW_EXTENSION __CRT_INLINE long long __cdecl llrintf (float x)
   {
-    long long retval;
+    __MINGW_EXTENSION long long retval;
     __fistpll(x, retval);
     return retval;
   }
 
-  __CRT_INLINE long long __cdecl llrintl (long double x)
+  __MINGW_EXTENSION __CRT_INLINE long long __cdecl llrintl (long double x)
   {
-    long long retval;
+    __MINGW_EXTENSION long long retval;
     __fistpll(x, retval);
     return retval;
   }
@@ -616,9 +616,9 @@ __CRT_INLINE int isinf (double d) {
   extern long __cdecl lroundf (float);
   extern long __cdecl lroundl (long double);
 
-  extern long long __cdecl llround (double);
-  extern long long __cdecl llroundf (float);
-  extern long long __cdecl llroundl (long double);
+  __MINGW_EXTENSION extern long long __cdecl llround (double);
+  __MINGW_EXTENSION extern long long __cdecl llroundf (float);
+  __MINGW_EXTENSION extern long long __cdecl llroundl (long double);
 
   /* 7.12.9.8 */
   /* round towards zero, regardless of fpu control word settings */
diff --git a/include/crt/rtcapi.h b/include/crt/rtcapi.h
index 9b3c48a3768..3816f2d25c8 100644
--- a/include/crt/rtcapi.h
+++ b/include/crt/rtcapi.h
@@ -70,10 +70,10 @@ extern "C" {
 
   char __fastcall _RTC_Check_2_to_1(short _Src);
   char __fastcall _RTC_Check_4_to_1(int _Src);
-  char __fastcall _RTC_Check_8_to_1(__int64 _Src);
+  __MINGW_EXTENSION char __fastcall _RTC_Check_8_to_1(__int64 _Src);
   short __fastcall _RTC_Check_4_to_2(int _Src);
-  short __fastcall _RTC_Check_8_to_2(__int64 _Src);
-  int __fastcall _RTC_Check_8_to_4(__int64 _Src);
+  __MINGW_EXTENSION short __fastcall _RTC_Check_8_to_2(__int64 _Src);
+  __MINGW_EXTENSION int __fastcall _RTC_Check_8_to_4(__int64 _Src);
 
 #if (defined(_X86_) && !defined(__x86_64))
   void __cdecl _RTC_CheckEsp();
diff --git a/include/crt/setjmp.h b/include/crt/setjmp.h
index 673b4b587cc..731640b17ac 100644
--- a/include/crt/setjmp.h
+++ b/include/crt/setjmp.h
@@ -34,8 +34,8 @@ extern "C" {
   } _JUMP_BUFFER;
 #elif defined(__ia64__)
   typedef _CRT_ALIGN(16) struct _SETJMP_FLOAT128 {
-    __int64 LowPart;
-    __int64 HighPart;
+    __MINGW_EXTENSION __int64 LowPart;
+    __MINGW_EXTENSION __int64 HighPart;
   } SETJMP_FLOAT128;
 
 #define _JBLEN 33
@@ -72,47 +72,47 @@ extern "C" {
     SETJMP_FLOAT128 FltS17;
     SETJMP_FLOAT128 FltS18;
     SETJMP_FLOAT128 FltS19;
-    __int64 FPSR;
-    __int64 StIIP;
-    __int64 BrS0;
-    __int64 BrS1;
-    __int64 BrS2;
-    __int64 BrS3;
-    __int64 BrS4;
-    __int64 IntS0;
-    __int64 IntS1;
-    __int64 IntS2;
-    __int64 IntS3;
-    __int64 RsBSP;
-    __int64 RsPFS;
-    __int64 ApUNAT;
-    __int64 ApLC;
-    __int64 IntSp;
-    __int64 IntNats;
-    __int64 Preds;
+    __MINGW_EXTENSION __int64 FPSR;
+    __MINGW_EXTENSION __int64 StIIP;
+    __MINGW_EXTENSION __int64 BrS0;
+    __MINGW_EXTENSION __int64 BrS1;
+    __MINGW_EXTENSION __int64 BrS2;
+    __MINGW_EXTENSION __int64 BrS3;
+    __MINGW_EXTENSION __int64 BrS4;
+    __MINGW_EXTENSION __int64 IntS0;
+    __MINGW_EXTENSION __int64 IntS1;
+    __MINGW_EXTENSION __int64 IntS2;
+    __MINGW_EXTENSION __int64 IntS3;
+    __MINGW_EXTENSION __int64 RsBSP;
+    __MINGW_EXTENSION __int64 RsPFS;
+    __MINGW_EXTENSION __int64 ApUNAT;
+    __MINGW_EXTENSION __int64 ApLC;
+    __MINGW_EXTENSION __int64 IntSp;
+    __MINGW_EXTENSION __int64 IntNats;
+    __MINGW_EXTENSION __int64 Preds;
 
   } _JUMP_BUFFER;
 #elif defined(__x86_64)
   typedef _CRT_ALIGN(16) struct _SETJMP_FLOAT128 {
-    unsigned __int64 Part[2];
+    __MINGW_EXTENSION unsigned __int64 Part[2];
   } SETJMP_FLOAT128;
 
 #define _JBLEN 16
   typedef SETJMP_FLOAT128 _JBTYPE;
 
   typedef struct _JUMP_BUFFER {
-    unsigned __int64 Frame;
-    unsigned __int64 Rbx;
-    unsigned __int64 Rsp;
-    unsigned __int64 Rbp;
-    unsigned __int64 Rsi;
-    unsigned __int64 Rdi;
-    unsigned __int64 R12;
-    unsigned __int64 R13;
-    unsigned __int64 R14;
-    unsigned __int64 R15;
-    unsigned __int64 Rip;
-    unsigned __int64 Spare;
+    __MINGW_EXTENSION unsigned __int64 Frame;
+    __MINGW_EXTENSION unsigned __int64 Rbx;
+    __MINGW_EXTENSION unsigned __int64 Rsp;
+    __MINGW_EXTENSION unsigned __int64 Rbp;
+    __MINGW_EXTENSION unsigned __int64 Rsi;
+    __MINGW_EXTENSION unsigned __int64 Rdi;
+    __MINGW_EXTENSION unsigned __int64 R12;
+    __MINGW_EXTENSION unsigned __int64 R13;
+    __MINGW_EXTENSION unsigned __int64 R14;
+    __MINGW_EXTENSION unsigned __int64 R15;
+    __MINGW_EXTENSION unsigned __int64 Rip;
+    __MINGW_EXTENSION unsigned __int64 Spare;
     SETJMP_FLOAT128 Xmm6;
     SETJMP_FLOAT128 Xmm7;
     SETJMP_FLOAT128 Xmm8;
diff --git a/include/crt/stddef.h b/include/crt/stddef.h
index 8aa692e540a..9482677272d 100644
--- a/include/crt/stddef.h
+++ b/include/crt/stddef.h
@@ -148,7 +148,7 @@ _TYPE_wchar_t;
 #endif
 #ifndef _PTRDIFF_T_DEFINED
 #define _PTRDIFF_T_DEFINED
-typedef __PTRDIFF_TYPE__ ptrdiff_t;
+__MINGW_EXTENSION typedef __PTRDIFF_TYPE__ ptrdiff_t;
 #endif
 #endif /* _GCC_PTRDIFF_T */
 #endif /* ___int_ptrdiff_t_h */
@@ -215,7 +215,7 @@ typedef __PTRDIFF_TYPE__ ptrdiff_t;
 #endif
 #endif
 #if !(defined (__GNUG__) && defined (size_t))
-typedef __SIZE_TYPE__ size_t;
+__MINGW_EXTENSION typedef __SIZE_TYPE__ size_t;
 #ifdef __BEOS__
 typedef long ssize_t;
 #endif /* __BEOS__ */
diff --git a/include/crt/stdint.h b/include/crt/stdint.h
index 30f58bd6071..4c99ed04414 100644
--- a/include/crt/stdint.h
+++ b/include/crt/stdint.h
@@ -38,8 +38,8 @@ typedef short  int16_t;
 typedef unsigned short  uint16_t;
 typedef int  int32_t;
 typedef unsigned   uint32_t;
-typedef long long  int64_t;
-typedef unsigned long long   uint64_t;
+__MINGW_EXTENSION typedef long long  int64_t;
+__MINGW_EXTENSION typedef unsigned long long   uint64_t;
 
 /* 7.18.1.2  Minimum-width integer types */
 typedef signed char int_least8_t;
@@ -48,8 +48,8 @@ typedef short  int_least16_t;
 typedef unsigned short  uint_least16_t;
 typedef int  int_least32_t;
 typedef unsigned   uint_least32_t;
-typedef long long  int_least64_t;
-typedef unsigned long long   uint_least64_t;
+__MINGW_EXTENSION typedef long long  int_least64_t;
+__MINGW_EXTENSION typedef unsigned long long   uint_least64_t;
 
 /*  7.18.1.3  Fastest minimum-width integer types
  *  Not actually guaranteed to be fastest for all purposes
@@ -61,12 +61,12 @@ typedef short  int_fast16_t;
 typedef unsigned short  uint_fast16_t;
 typedef int  int_fast32_t;
 typedef unsigned  int  uint_fast32_t;
-typedef long long  int_fast64_t;
-typedef unsigned long long   uint_fast64_t;
+__MINGW_EXTENSION typedef long long  int_fast64_t;
+__MINGW_EXTENSION typedef unsigned long long   uint_fast64_t;
 
 /* 7.18.1.5  Greatest-width integer types */
-typedef long long  intmax_t;
-typedef unsigned long long   uintmax_t;
+__MINGW_EXTENSION typedef long long  intmax_t;
+__MINGW_EXTENSION typedef unsigned long long   uintmax_t;
 
 /* 7.18.2  Limits of specified-width integer types */
 #if !defined ( __cplusplus) || defined (__STDC_LIMIT_MACROS)
diff --git a/include/crt/stdio.h b/include/crt/stdio.h
index 0125112da93..c056dce6c42 100644
--- a/include/crt/stdio.h
+++ b/include/crt/stdio.h
@@ -87,9 +87,9 @@ extern "C" {
 
 #ifndef _OFF64_T_DEFINED
 #define _OFF64_T_DEFINED
-  typedef long long _off64_t;
+  __MINGW_EXTENSION typedef long long _off64_t;
 #if !defined(NO_OLDNAMES) || defined(_POSIX)
-  typedef long long off64_t;
+  __MINGW_EXTENSION typedef long long off64_t;
 #endif
 #endif
 
@@ -106,10 +106,10 @@ extern "C" {
 #undef _FPOSOFF
 
 #if (!defined(NO_OLDNAMES) || defined(__GNUC__)) && _INTEGRAL_MAX_BITS >= 64
-  typedef __int64 fpos_t;
+  __MINGW_EXTENSION typedef __int64 fpos_t;
 #define _FPOSOFF(fp) ((long)(fp))
 #else
-  typedef long long fpos_t;
+  __MINGW_EXTENSION typedef long long fpos_t;
 #define _FPOSOFF(fp) ((long)(fp))
 #endif
 
@@ -179,8 +179,8 @@ extern "C" {
   _CRTIMP int __cdecl fsetpos(FILE *_File,const fpos_t *_Pos);
   _CRTIMP int __cdecl fseek(FILE *_File,long _Offset,int _Origin);
   _CRTIMP long __cdecl ftell(FILE *_File);
-  _CRTIMP int __cdecl _fseeki64(FILE *_File,__int64 _Offset,int _Origin);
-  _CRTIMP __int64 __cdecl _ftelli64(FILE *_File);
+  __MINGW_EXTENSION _CRTIMP int __cdecl _fseeki64(FILE *_File,__int64 _Offset,int _Origin);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _ftelli64(FILE *_File);
   _CRTIMP size_t __cdecl fwrite(const void *_Str,size_t _Size,size_t _Count,FILE *_File);
   _CRTIMP int __cdecl getc(FILE *_File);
   _CRTIMP int __cdecl getchar(void);
@@ -381,8 +381,8 @@ extern "C" {
   _CRTIMP size_t __cdecl _fread_nolock(void *_DstBuf,size_t _ElementSize,size_t _Count,FILE *_File);
   _CRTIMP int __cdecl _fseek_nolock(FILE *_File,long _Offset,int _Origin);
   _CRTIMP long __cdecl _ftell_nolock(FILE *_File);
-  _CRTIMP int __cdecl _fseeki64_nolock(FILE *_File,__int64 _Offset,int _Origin);
-  _CRTIMP __int64 __cdecl _ftelli64_nolock(FILE *_File);
+  __MINGW_EXTENSION _CRTIMP int __cdecl _fseeki64_nolock(FILE *_File,__int64 _Offset,int _Origin);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _ftelli64_nolock(FILE *_File);
   _CRTIMP size_t __cdecl _fwrite_nolock(const void *_DstBuf,size_t _Size,size_t _Count,FILE *_File);
   _CRTIMP int __cdecl _ungetc_nolock(int _Ch,FILE *_File);
 
diff --git a/include/crt/stdlib.h b/include/crt/stdlib.h
index 09dd4a5e378..baa0d8d419a 100644
--- a/include/crt/stdlib.h
+++ b/include/crt/stdlib.h
@@ -328,7 +328,7 @@ extern "C" {
 #endif
 
 #if _INTEGRAL_MAX_BITS >= 64
-  __int64 __cdecl _abs64(__int64);
+  __MINGW_EXTENSION __int64 __cdecl _abs64(__int64);
 #endif
   int __cdecl atexit(void (__cdecl *)(void));
 #ifndef _CRT_ATOF_DEFINED
@@ -348,20 +348,20 @@ extern "C" {
   unsigned short __cdecl _byteswap_ushort(unsigned short _Short);
   /*unsigned long __cdecl _byteswap_ulong (unsigned long _Long); */
 #if _INTEGRAL_MAX_BITS >= 64
-  unsigned __int64 __cdecl _byteswap_uint64(unsigned __int64 _Int64);
+  __MINGW_EXTENSION unsigned __int64 __cdecl _byteswap_uint64(unsigned __int64 _Int64);
 #endif
   div_t __cdecl div(int _Numerator,int _Denominator);
   char *__cdecl getenv(const char *_VarName);
   _CRTIMP char *__cdecl _itoa(int _Value,char *_Dest,int _Radix);
 #if _INTEGRAL_MAX_BITS >= 64
-  _CRTIMP char *__cdecl _i64toa(__int64 _Val,char *_DstBuf,int _Radix);
-  _CRTIMP char *__cdecl _ui64toa(unsigned __int64 _Val,char *_DstBuf,int _Radix);
-  _CRTIMP __int64 __cdecl _atoi64(const char *_String);
-  _CRTIMP __int64 __cdecl _atoi64_l(const char *_String,_locale_t _Locale);
-  _CRTIMP __int64 __cdecl _strtoi64(const char *_String,char **_EndPtr,int _Radix);
-  _CRTIMP __int64 __cdecl _strtoi64_l(const char *_String,char **_EndPtr,int _Radix,_locale_t _Locale);
-  _CRTIMP unsigned __int64 __cdecl _strtoui64(const char *_String,char **_EndPtr,int _Radix);
-  _CRTIMP unsigned __int64 __cdecl _strtoui64_l(const char *_String,char **_EndPtr,int _Radix,_locale_t _Locale);
+  __MINGW_EXTENSION _CRTIMP char *__cdecl _i64toa(__int64 _Val,char *_DstBuf,int _Radix);
+  __MINGW_EXTENSION _CRTIMP char *__cdecl _ui64toa(unsigned __int64 _Val,char *_DstBuf,int _Radix);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _atoi64(const char *_String);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _atoi64_l(const char *_String,_locale_t _Locale);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _strtoi64(const char *_String,char **_EndPtr,int _Radix);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _strtoi64_l(const char *_String,char **_EndPtr,int _Radix,_locale_t _Locale);
+  __MINGW_EXTENSION _CRTIMP unsigned __int64 __cdecl _strtoui64(const char *_String,char **_EndPtr,int _Radix);
+  __MINGW_EXTENSION _CRTIMP unsigned __int64 __cdecl _strtoui64_l(const char *_String,char **_EndPtr,int _Radix,_locale_t _Locale);
 #endif
   ldiv_t __cdecl ldiv(long _Numerator,long _Denominator);
   _CRTIMP char *__cdecl _ltoa(long _Value,char *_Dest,int _Radix);
@@ -445,14 +445,14 @@ extern "C" {
   _CRTIMP long __cdecl _wtol_l(const wchar_t *_Str,_locale_t _Locale);
 
 #if _INTEGRAL_MAX_BITS >= 64
-  _CRTIMP wchar_t *__cdecl _i64tow(__int64 _Val,wchar_t *_DstBuf,int _Radix);
-  _CRTIMP wchar_t *__cdecl _ui64tow(unsigned __int64 _Val,wchar_t *_DstBuf,int _Radix);
-  _CRTIMP __int64 __cdecl _wtoi64(const wchar_t *_Str);
-  _CRTIMP __int64 __cdecl _wtoi64_l(const wchar_t *_Str,_locale_t _Locale);
-  _CRTIMP __int64 __cdecl _wcstoi64(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix);
-  _CRTIMP __int64 __cdecl _wcstoi64_l(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix,_locale_t _Locale);
-  _CRTIMP unsigned __int64 __cdecl _wcstoui64(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix);
-  _CRTIMP unsigned __int64 __cdecl _wcstoui64_l(const wchar_t *_Str ,wchar_t **_EndPtr,int _Radix,_locale_t _Locale);
+  __MINGW_EXTENSION _CRTIMP wchar_t *__cdecl _i64tow(__int64 _Val,wchar_t *_DstBuf,int _Radix);
+  __MINGW_EXTENSION _CRTIMP wchar_t *__cdecl _ui64tow(unsigned __int64 _Val,wchar_t *_DstBuf,int _Radix);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _wtoi64(const wchar_t *_Str);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _wtoi64_l(const wchar_t *_Str,_locale_t _Locale);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _wcstoi64(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _wcstoi64_l(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix,_locale_t _Locale);
+  __MINGW_EXTENSION _CRTIMP unsigned __int64 __cdecl _wcstoui64(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix);
+  __MINGW_EXTENSION _CRTIMP unsigned __int64 __cdecl _wcstoui64_l(const wchar_t *_Str ,wchar_t **_EndPtr,int _Radix,_locale_t _Locale);
 #endif
 #endif
 
@@ -480,11 +480,11 @@ extern "C" {
   _CRTIMP int __cdecl _putenv(const char *_EnvString);
   unsigned int __cdecl _rotl(unsigned int _Val,int _Shift);
 #if _INTEGRAL_MAX_BITS >= 64
-  unsigned __int64 __cdecl _rotl64(unsigned __int64 _Val,int _Shift);
+  __MINGW_EXTENSION unsigned __int64 __cdecl _rotl64(unsigned __int64 _Val,int _Shift);
 #endif
   unsigned int __cdecl _rotr(unsigned int _Val,int _Shift);
 #if _INTEGRAL_MAX_BITS >= 64
-  unsigned __int64 __cdecl _rotr64(unsigned __int64 _Val,int _Shift);
+  __MINGW_EXTENSION unsigned __int64 __cdecl _rotr64(unsigned __int64 _Val,int _Shift);
 #endif
   _CRTIMP void __cdecl _searchenv(const char *_Filename,const char *_EnvVar,char *_ResultPath);
   _CRTIMP void __cdecl _splitpath(const char *_FullPath,char *_Drive,char *_Dir,char *_Filename,char *_Ext);
@@ -541,32 +541,32 @@ extern "C" {
 
 #if !defined __NO_ISOCEXT /* externs in static libmingwex.a */
 
-  typedef struct { long long quot, rem; } lldiv_t;
+  __MINGW_EXTENSION typedef struct { long long quot, rem; } lldiv_t;
 
-  lldiv_t __cdecl lldiv(long long, long long);
+  __MINGW_EXTENSION lldiv_t __cdecl lldiv(long long, long long);
 
-  __CRT_INLINE long long __cdecl llabs(long long _j) { return (_j >= 0 ? _j : -_j); }
+  __MINGW_EXTENSION __CRT_INLINE long long __cdecl llabs(long long _j) { return (_j >= 0 ? _j : -_j); }
 
-  long long  __cdecl strtoll(const char* __restrict__, char** __restrict, int);
-  unsigned long long  __cdecl strtoull(const char* __restrict__, char** __restrict__, int);
+  __MINGW_EXTENSION long long  __cdecl strtoll(const char* __restrict__, char** __restrict, int);
+  __MINGW_EXTENSION unsigned long long  __cdecl strtoull(const char* __restrict__, char** __restrict__, int);
 
   /* these are stubs for MS _i64 versions */
-  long long  __cdecl atoll (const char *);
+  __MINGW_EXTENSION long long  __cdecl atoll (const char *);
 
 #ifndef __STRICT_ANSI__
-  long long  __cdecl wtoll (const wchar_t *);
-  char *__cdecl lltoa (long long, char *, int);
-  char *__cdecl ulltoa (unsigned long long , char *, int);
-  wchar_t *__cdecl lltow (long long, wchar_t *, int);
-  wchar_t *__cdecl ulltow (unsigned long long, wchar_t *, int);
+  __MINGW_EXTENSION long long  __cdecl wtoll (const wchar_t *);
+  __MINGW_EXTENSION char *__cdecl lltoa (long long, char *, int);
+  __MINGW_EXTENSION char *__cdecl ulltoa (unsigned long long , char *, int);
+  __MINGW_EXTENSION wchar_t *__cdecl lltow (long long, wchar_t *, int);
+  __MINGW_EXTENSION wchar_t *__cdecl ulltow (unsigned long long, wchar_t *, int);
 
   /* __CRT_INLINE using non-ansi functions */
-  __CRT_INLINE long long  __cdecl atoll (const char * _c) { return _atoi64 (_c); }
-  __CRT_INLINE char *__cdecl lltoa (long long _n, char * _c, int _i) { return _i64toa (_n, _c, _i); }
-  __CRT_INLINE char *__cdecl ulltoa (unsigned long long _n, char * _c, int _i) { return _ui64toa (_n, _c, _i); }
-  __CRT_INLINE long long  __cdecl wtoll (const wchar_t * _w) { return _wtoi64 (_w); }
-  __CRT_INLINE wchar_t *__cdecl lltow (long long _n, wchar_t * _w, int _i) { return _i64tow (_n, _w, _i); }
-  __CRT_INLINE wchar_t *__cdecl ulltow (unsigned long long _n, wchar_t * _w, int _i) { return _ui64tow (_n, _w, _i); }
+  __MINGW_EXTENSION __CRT_INLINE long long  __cdecl atoll (const char * _c) { return _atoi64 (_c); }
+  __MINGW_EXTENSION __CRT_INLINE char *__cdecl lltoa (long long _n, char * _c, int _i) { return _i64toa (_n, _c, _i); }
+  __MINGW_EXTENSION __CRT_INLINE char *__cdecl ulltoa (unsigned long long _n, char * _c, int _i) { return _ui64toa (_n, _c, _i); }
+  __MINGW_EXTENSION __CRT_INLINE long long  __cdecl wtoll (const wchar_t * _w) { return _wtoi64 (_w); }
+  __MINGW_EXTENSION __CRT_INLINE wchar_t *__cdecl lltow (long long _n, wchar_t * _w, int _i) { return _i64tow (_n, _w, _i); }
+  __MINGW_EXTENSION __CRT_INLINE wchar_t *__cdecl ulltow (unsigned long long _n, wchar_t * _w, int _i) { return _ui64tow (_n, _w, _i); }
 #endif /* (__STRICT_ANSI__)  */
 
 #endif /* !__NO_ISOCEXT */
diff --git a/include/crt/time.h b/include/crt/time.h
index d09a8d9163a..75da425e3a1 100644
--- a/include/crt/time.h
+++ b/include/crt/time.h
@@ -29,7 +29,7 @@ extern "C" {
 #if defined(__GNUC__) && defined(__STRICT_ANSI__)
   typedef int _time64_t __attribute__ ((mode (DI)));
 #else
-  typedef __int64 __time64_t;
+  __MINGW_EXTENSION typedef __int64 __time64_t;
 #endif
 #endif
 #endif
@@ -55,7 +55,7 @@ extern "C" {
 #if defined(__GNUC__) && defined(__STRICT_ANSI__)
   typedef unsigned int size_t __attribute__ ((mode (DI)));
 #else
-  typedef unsigned __int64 size_t;
+  __MINGW_EXTENSION typedef unsigned __int64 size_t;
 #endif
 #else
   typedef unsigned int size_t;
diff --git a/include/crt/vadefs.h b/include/crt/vadefs.h
index ddc3e3af0a7..6a72792d171 100644
--- a/include/crt/vadefs.h
+++ b/include/crt/vadefs.h
@@ -29,7 +29,7 @@ extern "C" {
 #if defined(__GNUC__) && defined(__STRICT_ANSI__)
   typedef unsigned int uintptr_t __attribute__ ((mode (DI)));
 #else
-  typedef unsigned __int64 uintptr_t;
+  __MINGW_EXTENSION typedef unsigned __int64 uintptr_t;
 #endif
 #else
   typedef unsigned long uintptr_t;
diff --git a/include/crt/wchar.h b/include/crt/wchar.h
index c2f30b5007a..f70dfbbc6a2 100644
--- a/include/crt/wchar.h
+++ b/include/crt/wchar.h
@@ -93,7 +93,7 @@ extern "C" {
     time_t time_create;
     time_t time_access;
     time_t time_write;
-    __int64 size;
+    __MINGW_EXTENSION __int64 size;
     wchar_t name[260];
   };
 
@@ -102,7 +102,7 @@ extern "C" {
     __time32_t time_create;
     __time32_t time_access;
     __time32_t time_write;
-    __int64 size;
+    __MINGW_EXTENSION __int64 size;
     wchar_t name[260];
   };
 
@@ -120,7 +120,7 @@ extern "C" {
     __time64_t time_create;
     __time64_t time_access;
     __time64_t time_write;
-    __int64 size;
+    __MINGW_EXTENSION __int64 size;
     wchar_t name[260];
   };
 #endif
@@ -352,9 +352,9 @@ _CRTIMP int __cdecl iswblank(wint_t _C);
 
 #ifndef _OFF64_T_DEFINED
 #define _OFF64_T_DEFINED
-  typedef long long _off64_t;
+  __MINGW_EXTENSION typedef long long _off64_t;
 #ifndef NO_OLDNAMES
-  typedef long long off64_t;
+  __MINGW_EXTENSION typedef long long off64_t;
 #endif
 #endif
 
@@ -415,7 +415,7 @@ _CRTIMP int __cdecl iswblank(wint_t _C);
     short st_uid;
     short st_gid;
     _dev_t st_rdev;
-    __int64 st_size;
+    __MINGW_EXTENSION __int64 st_size;
     __time32_t st_atime;
     __time32_t st_mtime;
     __time32_t st_ctime;
@@ -443,7 +443,7 @@ _CRTIMP int __cdecl iswblank(wint_t _C);
     short st_uid;
     short st_gid;
     _dev_t st_rdev;
-    __int64 st_size;
+    __MINGW_EXTENSION __int64 st_size;
     __time64_t st_atime;
     __time64_t st_mtime;
     __time64_t st_ctime;
@@ -645,14 +645,14 @@ _CRTIMP int __cdecl iswblank(wint_t _C);
   _CRTIMP long __cdecl _wtol_l(const wchar_t *_Str,_locale_t _Locale);
 
 #if _INTEGRAL_MAX_BITS >= 64
-  _CRTIMP wchar_t *__cdecl _i64tow(__int64 _Val,wchar_t *_DstBuf,int _Radix);
-  _CRTIMP wchar_t *__cdecl _ui64tow(unsigned __int64 _Val,wchar_t *_DstBuf,int _Radix);
-  _CRTIMP __int64 __cdecl _wtoi64(const wchar_t *_Str);
-  _CRTIMP __int64 __cdecl _wtoi64_l(const wchar_t *_Str,_locale_t _Locale);
-  _CRTIMP __int64 __cdecl _wcstoi64(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix);
-  _CRTIMP __int64 __cdecl _wcstoi64_l(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix,_locale_t _Locale);
-  _CRTIMP unsigned __int64 __cdecl _wcstoui64(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix);
-  _CRTIMP unsigned __int64 __cdecl _wcstoui64_l(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix,_locale_t _Locale);
+  __MINGW_EXTENSION _CRTIMP wchar_t *__cdecl _i64tow(__int64 _Val,wchar_t *_DstBuf,int _Radix);
+  __MINGW_EXTENSION _CRTIMP wchar_t *__cdecl _ui64tow(unsigned __int64 _Val,wchar_t *_DstBuf,int _Radix);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _wtoi64(const wchar_t *_Str);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _wtoi64_l(const wchar_t *_Str,_locale_t _Locale);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _wcstoi64(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix);
+  __MINGW_EXTENSION _CRTIMP __int64 __cdecl _wcstoi64_l(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix,_locale_t _Locale);
+  __MINGW_EXTENSION _CRTIMP unsigned __int64 __cdecl _wcstoui64(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix);
+  __MINGW_EXTENSION _CRTIMP unsigned __int64 __cdecl _wcstoui64_l(const wchar_t *_Str,wchar_t **_EndPtr,int _Radix,_locale_t _Locale);
 #endif
 #endif
 
@@ -782,8 +782,8 @@ __CRT_INLINE wchar_t *__cdecl _wctime(const time_t *_Time) { return _wctime64(_T
   int wmemcmp(const wchar_t *s1, const wchar_t *s2,size_t n);
   wchar_t *__cdecl wmemcpy(wchar_t *s1,const wchar_t *s2,size_t n);
   wchar_t *__cdecl wmemmove(wchar_t *s1, const wchar_t *s2, size_t n);
-  long long __cdecl wcstoll(const wchar_t *nptr,wchar_t **endptr, int base);
-  unsigned long long __cdecl wcstoull(const wchar_t *nptr,wchar_t **endptr, int base);
+  __MINGW_EXTENSION long long __cdecl wcstoll(const wchar_t *nptr,wchar_t **endptr, int base);
+  __MINGW_EXTENSION unsigned long long __cdecl wcstoull(const wchar_t *nptr,wchar_t **endptr, int base);
 #endif /* __NO_ISOCEXT */
 
   void *__cdecl memmove(void *_Dst,const void *_Src,size_t _MaxCount);