diff --git a/dll/win32/msvcrt/msvcrt.spec b/dll/win32/msvcrt/msvcrt.spec
index 848e2602e45..4ecdd97de49 100644
--- a/dll/win32/msvcrt/msvcrt.spec
+++ b/dll/win32/msvcrt/msvcrt.spec
@@ -1185,7 +1185,7 @@
 @ cdecl -version=0x600+ _wctime64_s(ptr long ptr)
 @ stub -version=0x600+ _wctomb_l
 @ stub -version=0x600+ _wctomb_s_l
-# stub _wctype
+@ extern _wctype
 @ extern _wenviron
 @ varargs _wexecl(wstr wstr)
 @ varargs _wexecle(wstr wstr)
diff --git a/modules/rostests/apitests/crt/crtdata.c b/modules/rostests/apitests/crt/crtdata.c
new file mode 100644
index 00000000000..2022d43e81e
--- /dev/null
+++ b/modules/rostests/apitests/crt/crtdata.c
@@ -0,0 +1,640 @@
+/*
+* PROJECT:         ReactOS CRT API tests
+* LICENSE:         GPL-2.0-or-later (https://spdx.org/licenses/GPL-2.0-or-later)
+* PURPOSE:         Tests for crt data exports
+* COPYRIGHT:       Copyright 2021 Timo Kreuzer <timo.kreuzer@reactos.org>
+*/
+
+#include <apitest.h>
+#include <apitest_guard.h>
+
+#define WIN32_NO_STATUS
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <locale.h>
+#include <mbctype.h>
+
+static OSVERSIONINFOW s_osvi;
+extern char __ImageBase;
+static void* s_ImageEnd;
+
+int IsLocalSymbol(void* Address)
+{
+    return ((Address >= (void*)&__ImageBase) && (Address <= s_ImageEnd));
+}
+
+#ifndef TEST_STATIC
+#define test_is_local_symbol(addr, is) ok_int(IsLocalSymbol(addr), (is))
+#else
+#define test_is_local_symbol(addr, is)
+#endif
+
+void Test___argc(void)
+{
+    void* p = &__argc;
+    test_is_local_symbol(p, FALSE);
+
+    #undef __argc
+    ok_ptr(&__argc, p);
+#ifdef _M_IX86
+    ok_ptr(__p___argc(), p);
+#endif
+}
+
+void Test___argv(void)
+{
+    void* p = &__argv;
+    test_is_local_symbol(p, FALSE);
+
+    #undef __argv
+    ok_ptr(&__argv, p);
+#ifdef _M_IX86
+    ok_ptr(__p___argv(), p);
+#endif
+}
+
+void Test___badioinfo(void)
+{
+    typedef struct _ioinfo ioinfo;
+    _CRTIMP extern ioinfo* __badioinfo[];
+    ok(__badioinfo != NULL, "__badioinfo is NULL\n");
+    ok(__badioinfo[0] != NULL, "__badioinfo is NULL\n");
+}
+
+void Test___initenv(void)
+{
+    _CRTIMP extern char** __initenv;
+    ok(__initenv != NULL, "__initenv is NULL\n");
+    ok(*__initenv != NULL, "*__initenv is NULL\n");
+#ifdef _M_IX86
+    _CRTIMP char*** __p___initenv(void);
+    ok_ptr(__p___initenv(), &__initenv);
+#endif
+}
+
+void Test___lc_codepage(void)
+{
+    _CRTIMP extern unsigned int __lc_codepage;
+    ok_int(__lc_codepage, 0);
+    ok_int(___lc_codepage_func(), 0);
+    __lc_codepage++;
+    todo_ros ok_int(___lc_codepage_func(), 0);
+    __lc_codepage--;
+}
+
+void Test___lc_collate_cp(void)
+{
+    _CRTIMP extern int __lc_collate_cp;
+    test_is_local_symbol(&__lc_collate_cp, FALSE);
+    ok_int(__lc_collate_cp, 0);
+    ok_int(___lc_collate_cp_func(), 0);
+    __lc_collate_cp++;
+    ok_int(___lc_collate_cp_func(), 0);
+    __lc_collate_cp--;
+}
+
+void Test___lc_handle(void)
+{
+    _CRTIMP int __lc_handle;
+    ok_int(__lc_handle, 0);
+    _CRTIMP int* ___lc_handle_func();
+    ok_int(*___lc_handle_func(), 0);
+    __lc_handle++;
+    todo_ros ok_int(*___lc_handle_func(), 0);
+    __lc_handle--;
+}
+
+void Test___mb_cur_max(void)
+{
+    void* p = &__mb_cur_max;
+    test_is_local_symbol(&__mb_cur_max, FALSE);
+    ok_int(__mb_cur_max, 1);
+
+    #undef __mb_cur_max
+    _CRTIMP extern int __mb_cur_max;
+    ok_ptr(&__mb_cur_max, p);
+
+    ok_int(___mb_cur_max_func(), 1);
+#ifdef _M_IX86
+    _CRTIMP int* __p___mb_cur_max(void);
+    ok_int(*__p___mb_cur_max(), 1);
+#endif
+    __mb_cur_max++;
+    if (s_osvi.dwMajorVersion >= 6)
+    {
+        ok_int(___mb_cur_max_func(), 1);
+#ifdef _M_IX86
+        ok_int(*__p___mb_cur_max(), 1);
+#endif
+    }
+    else
+    {
+        todo_ros ok_int(___mb_cur_max_func(), 2);
+#ifdef _M_IX86
+        todo_ros ok_ptr(__p___mb_cur_max(), p); // wine code handles it like on Vista+
+        todo_ros ok_int(*__p___mb_cur_max(), 2);
+#endif
+    }
+
+    __mb_cur_max--;
+}
+
+void Test___pioinfo(void)
+{
+
+}
+
+void Test___setlc_active(void)
+{
+    _CRTIMP extern unsigned int __setlc_active;
+    ok_int(__setlc_active, 0);
+
+    _CRTIMP unsigned int ___setlc_active_func(void);
+    ok_int(___setlc_active_func(), __setlc_active);
+    __setlc_active++;
+    ok_int(___setlc_active_func(), __setlc_active);
+    __setlc_active--;
+}
+
+void Test___unguarded_readlc_active(void)
+{
+    _CRTIMP extern unsigned int __unguarded_readlc_active;
+    void* p = &__unguarded_readlc_active;
+    ok_int(__unguarded_readlc_active, 0);
+
+    _CRTIMP unsigned int* ___unguarded_readlc_active_add_func(void);
+    ok_ptr(___unguarded_readlc_active_add_func(), p);
+}
+
+void Test___wargv(void)
+{
+    void* p = &__wargv;
+    test_is_local_symbol(p, FALSE);
+
+    #undef __wargv
+    _CRTIMP extern wchar_t ** __wargv;
+    ok_ptr(&__wargv, p);
+#ifdef _M_IX86
+    ok_ptr(__p___wargv(), p);
+#endif
+}
+
+void Test___winitenv(void)
+{
+    _CRTIMP extern wchar_t** __winitenv;
+    todo_ros ok(__winitenv == NULL, "__winitenv is not NULL\n");
+#ifdef _M_IX86
+    _CRTIMP wchar_t*** __p___winitenv(void);
+    ok_ptr(__p___winitenv(), &__winitenv);
+#endif
+}
+
+void Test__acmdln(void)
+{
+    _CRTIMP extern char* _acmdln;
+    ok(_acmdln != NULL, "__winitenv is NULL\n");
+#ifdef _M_IX86
+    _CRTIMP char** __p__acmdln(void);
+    ok_ptr(__p__acmdln(), &_acmdln);
+#endif
+}
+
+#ifdef _M_IX86
+void Test__adjust_fdiv(void)
+{
+    _CRTIMP extern int _adjust_fdiv;
+    ok_int(_adjust_fdiv, 0);
+}
+#endif
+
+void Test__aexit_rtn(void)
+{
+    typedef void (*_exit_t)(int exitcode);
+    _CRTIMP extern _exit_t _aexit_rtn;
+    ok_ptr(_aexit_rtn, _exit);
+}
+
+void Test__commode(void)
+{
+    void* p = &_commode;
+    test_is_local_symbol(&_commode, FALSE);
+    ok_int(_commode, 0);
+
+    #undef _commode
+    _CRTIMP extern int _commode;
+    ok_ptr(&_commode, p);
+#ifdef _M_IX86
+    ok_ptr(__p__commode(), &_commode);
+#endif
+}
+
+void Test__ctype(void)
+{
+    _CRTIMP extern const unsigned short _ctype[];
+    ok_int(_ctype[0], 0);
+    ok_int(_ctype[1], _CONTROL);
+
+    #undef _pctype
+    _CRTIMP extern const unsigned short* _pctype;
+    ok(_pctype != &_ctype[0], "_pwctype should not match &_wctype[0]");
+    if (s_osvi.dwMajorVersion >= 6)
+    {
+        ok(_pctype != &_ctype[1], "_pwctype should not match &_wctype[1]");
+    }
+    else
+    {
+        ok(_pctype == &_ctype[1], "_pwctype should match &_wctype[1]");
+    }
+
+    ok(__pctype_func() != _ctype, "__pctype_func() should not match _ctype\n");
+    ok_int(__pctype_func()[0], _CONTROL);
+    ok_int(__pctype_func()[1], _CONTROL);
+#ifdef _M_IX86
+    _CRTIMP const unsigned short** __cdecl __p__pctype(void);
+    ok_ptr(*__p__pctype(), __pctype_func());
+#endif
+}
+
+void Test__wctype(void)
+{
+    ok_int(_wctype[0], 0);
+    ok_int(_wctype[1], _CONTROL);
+
+    #undef _pwctype
+    _CRTIMP extern const unsigned short* _pwctype;
+    ok_ptr(_pwctype, &_wctype[1]);
+
+    ok(__pwctype_func() != _wctype, "__pwctype_func() == _wctype\n");
+    ok_int(__pctype_func()[0], _CONTROL);
+    ok_int(__pctype_func()[1], _CONTROL);
+#ifdef _M_IX86
+    _CRTIMP const unsigned short** __cdecl __p__pwctype(void);
+    ok_ptr(*__p__pwctype(), __pwctype_func());
+#endif
+}
+
+void Test__daylight(void)
+{
+    void* p = &_daylight;
+    test_is_local_symbol(&_daylight, FALSE);
+
+    #undef _daylight
+    _CRTIMP extern int _daylight;
+    ok_ptr(&_daylight, p);
+
+#ifdef _M_IX86
+    _CRTIMP void* __p__daylight(void);
+    ok_ptr(__p__daylight(), &_daylight);
+#endif
+#if (WINVER >= 0x600)
+    _CRTIMP int* __cdecl __daylight(void);
+    ok_ptr(&__daylight, &_daylight);
+#endif
+}
+
+void Test__dstbias(void)
+{
+    void* p = &_dstbias;
+    test_is_local_symbol(&_dstbias, FALSE);
+
+    #undef _dstbias
+    _CRTIMP extern long _dstbias;
+    ok_ptr(&_dstbias, p);
+#ifdef _M_IX86
+    _CRTIMP long* __cdecl __p__dstbias(void);
+    ok_ptr(__p__dstbias(), &_dstbias);
+#endif
+#if (WINVER >= 0x600)
+    _CRTIMP long* __cdecl __dstbias(void);
+    ok_ptr(&__dstbias, &_dstbias);
+#endif
+}
+
+void Test__environ(void)
+{
+    void* p = &_environ;
+    ok(_environ != NULL, "_environ == NULL\n");
+
+    #undef _environ
+    _CRTIMP extern char** _environ;
+    ok_ptr(&_environ, p);
+#ifdef _M_IX86
+    ok_ptr(__p__environ(), &_environ);
+#endif
+}
+
+void Test__fileinfo(void)
+{
+    _CRTIMP extern int _fileinfo;
+    ok_int(_fileinfo, -1);
+
+#ifdef _M_IX86
+    _CRTIMP int* __p__fileinfo();
+    ok_ptr(__p__fileinfo(), &_fileinfo);
+#endif
+}
+
+void Test__fmode(void)
+{
+    void* p = &_fmode;
+    test_is_local_symbol(&_fmode, FALSE);
+    ok_int(_fmode, 0);
+
+    #undef _fmode
+    _CRTIMP extern int _fmode;
+    ok_ptr(&_fmode, p);
+
+#ifdef _M_IX86
+    _CRTIMP int* __cdecl __p__fmode();
+    ok_ptr(__p__fmode(), p);
+#endif
+
+#if (_WIN32_WINNT >= 0x600)
+    _fmode = 1234;
+    _CRTIMP errno_t __cdecl _get_fmode(_Out_ int* _PMode);
+    int mode;
+    ok_int(_get_fmode(&mode), 0);
+    ok_int(mode, _fmode);
+    _fmode = 0;
+#endif
+}
+
+void Test__iob(void)
+{
+    void* p = &_iob;
+    test_is_local_symbol(&_iob, FALSE);
+    ok_ptr(&_iob[0], stdin);
+    ok_ptr(&_iob[1], stdout);
+    ok_ptr(&_iob[2], stderr);
+
+    #undef _iob
+    _CRTIMP extern FILE _iob[];
+    ok_ptr(&_iob, p);
+
+    ok_ptr(__iob_func(), &_iob);
+
+#ifdef _M_IX86
+    _CRTIMP int* __cdecl __p__iob();
+    ok_ptr(__p__iob(), p);
+#endif
+}
+
+void Test__mbcasemap(void)
+{
+    void* p = &_mbcasemap;
+    ok_int(_mbcasemap[0], 0);
+
+    #undef _mbcasemap
+    ok_ptr(_mbcasemap, p);
+
+#ifdef _M_IX86
+    _CRTIMP unsigned char* __cdecl __p__mbcasemap();
+    ok_ptr(__p__mbcasemap(), &_mbcasemap);
+#endif
+}
+
+void Test__mbctype(void)
+{
+    void* p = &_mbctype;
+    ok_int(_mbctype[0], 0);
+
+    #undef _mbctype
+    ok_ptr(&_mbctype, p);
+
+#ifdef _M_IX86
+    _CRTIMP unsigned char* __cdecl __p__mbctype();
+    todo_ros ok_ptr(__p__mbctype(), &_mbctype); // wine implements thiss like on Vista
+#endif
+}
+
+void Test__osplatform(void)
+{
+    ok_int(_osplatform, s_osvi.dwPlatformId);
+#if (WINVER >= 0x600)
+    _CRTIMP unsigned int __cdecl _get_osplatform(void);
+    ok_ptr(_get_osplatform(), _osplatform);
+#endif
+}
+
+void Test__osver(void)
+{
+    ok_int(_osver, s_osvi.dwBuildNumber);
+
+#ifdef _M_IX86
+    _CRTIMP int* __cdecl __p__osver();
+    ok_ptr(__p__osver(), &_osver);
+#endif
+}
+
+void Test__pgmptr(void)
+{
+    void* p = &_pgmptr;
+    ok(_pgmptr != NULL, "_pgmptr should not be NULL\n");
+
+    #undef _pgmptr
+    _CRTIMP extern char* _pgmptr;
+    ok_ptr(&_pgmptr, p);
+#ifdef _M_IX86
+    ok_ptr(__p__pgmptr(), &_pgmptr);
+#endif
+#if (WINVER >= 0x600)
+    _CRTIMP char* __cdecl _get_pgmptr(void);
+    ok_ptr(_get_pgmptr(), _pgmptr);
+#endif
+}
+
+void Test__sys_errlist(void)
+{
+    void* p = &_sys_errlist;
+    ok_int(strcmp(_sys_errlist[0], strerror(0)), 0);
+    ok_int(strcmp(_sys_errlist[42], strerror(42)), 0);
+
+    #undef _sys_errlist
+    _CRTIMP extern char* _sys_errlist[];
+    ok_ptr(&_sys_errlist, p);
+}
+
+void Test__sys_nerr(void)
+{
+    void* p = &_sys_nerr;
+    ok_int(_sys_nerr, 43);
+
+    #undef _sys_nerr
+    _CRTIMP extern int _sys_nerr;
+    ok_ptr(&_sys_nerr, p);
+}
+
+void Test__timezone(void)
+{
+    void* p = &_timezone;
+    test_is_local_symbol(&_timezone, FALSE);
+
+    #undef _timezone
+    _CRTIMP extern long _timezone;
+    ok_ptr(&_timezone, p);
+
+#ifdef _M_IX86
+    _CRTIMP char** __p__timezone();
+    ok_ptr(__p__timezone(), &_timezone);
+#endif
+}
+
+void Test__tzname(void)
+{
+    void* p = &_tzname;
+    test_is_local_symbol(&_tzname, FALSE);
+    ok(_tzname[0] != NULL, "_tzname[0] == NULL\n");
+    ok(_tzname[0] != NULL, "_tzname[0] == NULL\n");
+
+    #undef _tzname
+    _CRTIMP extern char * _tzname[2];
+    ok_ptr(_tzname, p);
+
+#ifdef _M_IX86
+    _CRTIMP char** __p__tzname();
+    ok_ptr(__p__tzname(), &_tzname);
+#endif
+#if (WINVER >= 0x600)
+    _CRTIMP char* __cdecl __tzname(void);
+    ok_ptr(__tzname(), _wenviron);
+#endif
+}
+
+void Test__wcmdln(void)
+{
+    _CRTIMP extern wchar_t* _wcmdln;
+#ifdef _M_IX86
+    _CRTIMP wchar_t** __p__wcmdln(void);
+    ok_ptr(__p__wcmdln(), &_wcmdln);
+#endif
+}
+
+void Test__wenviron(void)
+{
+    void* p = &_wenviron;
+    todo_ros ok(_wenviron == NULL, "_wenviron is not NULL\n");
+
+    #undef _wenviron
+    _CRTIMP extern wchar_t** _wenviron;
+    ok_ptr(&_wenviron, p);
+#ifdef _M_IX86
+    ok_ptr(__p__wenviron(), &_wenviron);
+#endif
+#if (WINVER >= 0x600)
+    _CRTIMP unsigned int __cdecl _get_wenviron(void);
+    ok_int(_get_wenviron(), _wenviron);
+#endif
+}
+
+void Test__winmajor(void)
+{
+    ok_int(_winmajor, s_osvi.dwMajorVersion);
+#ifdef _M_IX86
+    _CRTIMP unsigned int* __cdecl __p__winmajor();
+    ok_ptr(__p__winmajor(), &_winmajor);
+#endif
+#if (WINVER >= 0x600)
+    _CRTIMP unsigned int __cdecl _get_winmajor(void);
+    ok_int(_get_winmajor(), _winmajor);
+#endif
+}
+
+void Test__winminor(void)
+{
+    ok_int(_winminor, s_osvi.dwMinorVersion);
+#ifdef _M_IX86
+    _CRTIMP unsigned int* __cdecl __p__winminor();
+    ok_ptr(__p__winminor(), &_winminor);
+#endif
+#if (WINVER >= 0x600)
+    _CRTIMP unsigned int __cdecl _get_winminor(void);
+    ok_int(_get_winminor(), _winminor);
+#endif
+}
+
+void Test__winver(void)
+{
+    ok_int(_winver, (s_osvi.dwMajorVersion << 8) | s_osvi.dwMinorVersion);
+#ifdef _M_IX86
+    _CRTIMP unsigned int* __cdecl __p__winver();
+    ok_ptr(__p__winver(), &_winver);
+#endif
+#if (WINVER >= 0x600)
+    _CRTIMP unsigned int __cdecl _get_winver(void);
+    ok_int(_get_winver(), _winver);
+#endif
+}
+
+void Test__wpgmptr(void)
+{
+    void* p = _wpgmptr;
+    ok_ptr(_wpgmptr, NULL);
+
+    #undef _wpgmptr
+    ok_ptr(_wpgmptr, p);
+
+#ifdef _M_IX86
+    _CRTIMP wchar_t ** __cdecl __p__wpgmptr();
+    ok_ptr(__p__wpgmptr(), &_wpgmptr);
+#endif
+#if (WINVER >= 0x600)
+    _CRTIMP unsigned int __cdecl _get_wpgmptr(void);
+    ok_int(_get_wpgmptr(), _wpgmptr);
+#endif
+}
+
+START_TEST(crtdata)
+{
+    /* Initialize image size */
+    PIMAGE_DOS_HEADER dosHeader = (PIMAGE_DOS_HEADER)&__ImageBase;
+    PIMAGE_NT_HEADERS ntHeaders = (PIMAGE_NT_HEADERS)((PUCHAR)dosHeader + dosHeader->e_lfanew);
+    s_ImageEnd = (PUCHAR)dosHeader + ntHeaders->OptionalHeader.SizeOfImage;
+
+    /* initialize version info */
+    s_osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFOW);
+    GetVersionExW(&s_osvi);
+
+    Test___argc();
+    Test___argv();
+    Test___badioinfo();
+    Test___initenv();
+    Test___lc_codepage();
+    Test___lc_collate_cp();
+    Test___lc_handle();
+    Test___mb_cur_max();
+    Test___pioinfo();
+    Test___setlc_active();
+    Test___unguarded_readlc_active();
+    Test___wargv();
+    Test___winitenv();
+    Test__acmdln();
+#ifdef _M_IX86
+    Test__adjust_fdiv();
+#endif
+    Test__aexit_rtn();
+    Test__commode();
+    Test__ctype();
+    Test__daylight();
+    Test__dstbias();
+    Test__environ();
+    Test__fileinfo();
+    Test__fmode();
+    Test__iob();
+    Test__mbcasemap();
+    Test__mbctype();
+    Test__osplatform();
+    Test__osver();
+    Test__pgmptr();
+    Test__sys_errlist();
+    Test__sys_nerr();
+    Test__timezone();
+    Test__tzname();
+    Test__wcmdln();
+    Test__wctype();
+    Test__wenviron();
+    Test__winmajor();
+    Test__winminor();
+    Test__winver();
+    Test__wpgmptr();
+}
diff --git a/modules/rostests/apitests/crt/msvcrt_crt_apitest.cmake b/modules/rostests/apitests/crt/msvcrt_crt_apitest.cmake
index 5c5bb587fbb..dcef3b0d582 100644
--- a/modules/rostests/apitests/crt/msvcrt_crt_apitest.cmake
+++ b/modules/rostests/apitests/crt/msvcrt_crt_apitest.cmake
@@ -1261,6 +1261,7 @@ list(APPEND SOURCE_MSVCRT
 #    wprintf_s.c
 #    wscanf.c
 #    wscanf_s.c
+    crtdata.c
     static_construct.cpp
     static_init.c
 )
diff --git a/modules/rostests/apitests/crt/testlist.c b/modules/rostests/apitests/crt/testlist.c
index 4c36c86eee4..dacd260e161 100644
--- a/modules/rostests/apitests/crt/testlist.c
+++ b/modules/rostests/apitests/crt/testlist.c
@@ -34,6 +34,7 @@ extern void func___getmainargs(void);
 
 extern void func_static_construct(void);
 extern void func_static_init(void);
+extern void func_crtdata(void);
 
 const struct test winetest_testlist[] =
 {
@@ -59,6 +60,7 @@ const struct test winetest_testlist[] =
 #if defined(TEST_STATIC_CRT)
 #elif defined(TEST_MSVCRT)
     { "atexit", func_atexit },
+    { "crtdata", func_crtdata },
 #if defined(_M_IX86)
     { "__getmainargs", func___getmainargs },
 #elif defined(_M_ARM)