diff --git a/dlls/msvcr120/msvcr120.spec b/dlls/msvcr120/msvcr120.spec
index 1773976481f..1d23526d805 100644
--- a/dlls/msvcr120/msvcr120.spec
+++ b/dlls/msvcr120/msvcr120.spec
@@ -1734,7 +1734,7 @@
 @ cdecl _strtof_l(str ptr ptr) MSVCRT__strtof_l
 @ cdecl -ret64 _strtoi64(str ptr long) MSVCRT_strtoi64
 @ cdecl -ret64 _strtoi64_l(str ptr long ptr) MSVCRT_strtoi64_l
-@ stub _strtoimax_l
+@ cdecl -ret64 _strtoimax_l(str ptr long ptr) MSVCRT_strtoi64_l
 @ cdecl _strtol_l(str ptr long ptr) MSVCRT__strtol_l
 @ stub _strtold_l
 @ cdecl -ret64 _strtoll_l(str ptr long ptr) MSVCRT_strtoi64_l
@@ -1742,7 +1742,7 @@
 @ cdecl -ret64 _strtoui64_l(str ptr long ptr) MSVCRT_strtoui64_l
 @ cdecl _strtoul_l(str ptr long ptr) MSVCRT_strtoul_l
 @ cdecl -ret64 _strtoull_l(str ptr long ptr) MSVCRT_strtoui64_l
-@ stub _strtoumax_l
+@ cdecl -ret64 _strtoumax_l(str ptr long ptr) MSVCRT_strtoui64_l
 @ cdecl _strupr(str) MSVCRT__strupr
 @ cdecl _strupr_l(str ptr) MSVCRT__strupr_l
 @ cdecl _strupr_s(str long) MSVCRT__strupr_s
@@ -2387,7 +2387,7 @@
 @ cdecl strstr(str str) MSVCRT_strstr
 @ cdecl strtod(str ptr) MSVCRT_strtod
 @ cdecl strtof(str ptr) MSVCRT_strtof
-@ stub strtoimax
+@ cdecl -ret64 strtoimax(str ptr long) MSVCRT_strtoi64
 @ cdecl strtok(str str) MSVCRT_strtok
 @ cdecl strtok_s(ptr str ptr) MSVCRT_strtok_s
 @ cdecl strtol(str ptr long) MSVCRT_strtol
@@ -2395,7 +2395,7 @@
 @ cdecl -ret64 strtoll(str ptr long) MSVCRT_strtoi64
 @ cdecl strtoul(str ptr long) MSVCRT_strtoul
 @ cdecl -ret64 strtoull(str ptr long) MSVCRT_strtoui64
-@ stub strtoumax
+@ cdecl -ret64 strtoumax(str ptr long) MSVCRT_strtoui64
 @ cdecl strxfrm(ptr str long) MSVCRT_strxfrm
 @ varargs swprintf_s(ptr long wstr) MSVCRT_swprintf_s
 @ varargs swscanf(wstr wstr) MSVCRT_swscanf
diff --git a/dlls/msvcr120_app/msvcr120_app.spec b/dlls/msvcr120_app/msvcr120_app.spec
index 8072349d8d0..d9e998c985e 100644
--- a/dlls/msvcr120_app/msvcr120_app.spec
+++ b/dlls/msvcr120_app/msvcr120_app.spec
@@ -1445,7 +1445,7 @@
 @ cdecl _strtof_l(str ptr ptr) msvcr120._strtof_l
 @ cdecl -ret64 _strtoi64(str ptr long) msvcr120._strtoi64
 @ cdecl -ret64 _strtoi64_l(str ptr long ptr) msvcr120._strtoi64_l
-@ stub _strtoimax_l
+@ cdecl -ret64 _strtoimax_l(str ptr long ptr) msvcr120._strtoimax_l
 @ cdecl _strtol_l(str ptr long ptr) msvcr120._strtol_l
 @ stub _strtold_l
 @ cdecl -ret64 _strtoll_l(str ptr long ptr) msvcr120._strtoll_l
@@ -1453,7 +1453,7 @@
 @ cdecl -ret64 _strtoui64_l(str ptr long ptr) msvcr120._strtoui64_l
 @ cdecl _strtoul_l(str ptr long ptr) msvcr120._strtoul_l
 @ cdecl -ret64 _strtoull_l(str ptr long ptr) msvcr120._strtoull_l
-@ stub _strtoumax_l
+@ cdecl -ret64 _strtoumax_l(str ptr long ptr) msvcr120._strtoumax_l
 @ cdecl _strupr(str) msvcr120._strupr
 @ cdecl _strupr_l(str ptr) msvcr120._strupr_l
 @ cdecl _strupr_s(str long) msvcr120._strupr_s
@@ -2050,7 +2050,7 @@
 @ cdecl strstr(str str) msvcr120.strstr
 @ cdecl strtod(str ptr) msvcr120.strtod
 @ cdecl strtof(str ptr) msvcr120.strtof
-@ stub strtoimax
+@ cdecl -ret64 strtoimax(str ptr long) msvcr120.strtoimax
 @ cdecl strtok(str str) msvcr120.strtok
 @ cdecl strtok_s(ptr str ptr) msvcr120.strtok_s
 @ cdecl strtol(str ptr long) msvcr120.strtol
@@ -2058,7 +2058,7 @@
 @ cdecl -ret64 strtoll(str ptr long) msvcr120.strtoll
 @ cdecl strtoul(str ptr long) msvcr120.strtoul
 @ cdecl -ret64 strtoull(str ptr long) msvcr120.strtoull
-@ stub strtoumax
+@ cdecl -ret64 strtoumax(str ptr long) msvcr120.strtoumax
 @ cdecl strxfrm(ptr str long) msvcr120.strxfrm
 @ varargs swprintf_s(ptr long wstr) msvcr120.swprintf_s
 @ varargs swscanf(wstr wstr) msvcr120.swscanf
diff --git a/include/msvcrt/stdlib.h b/include/msvcrt/stdlib.h
index f14256c18f6..00acd374346 100644
--- a/include/msvcrt/stdlib.h
+++ b/include/msvcrt/stdlib.h
@@ -215,6 +215,10 @@ __msvcrt_long __cdecl strtol(const char*,char**,int);
 __msvcrt_ulong __cdecl strtoul(const char*,char**,int);
 __int64       __cdecl strtoll_l(const char*,char**,int,_locale_t);
 unsigned __int64 __cdecl strtoull_l(const char*,char**,int,_locale_t);
+__int64       __cdecl strtoimax(const char*,char**,int);
+__int64       __cdecl strtoimax_l(const char*,char**,int,_locale_t);
+unsigned __int64 __cdecl strtoumax(const char*,char**,int);
+unsigned __int64 __cdecl strtoumax_l(const char*,char**,int,_locale_t);
 __int64       __cdecl _strtoi64(const char*,char**,int);
 __int64       __cdecl _strtoi64_l(const char*,char**,int,_locale_t);
 unsigned __int64 __cdecl _strtoui64(const char*,char**,int);