diff --git a/tcc.h b/tcc.h
index aa04404a..ac50a6da 100644
--- a/tcc.h
+++ b/tcc.h
@@ -65,12 +65,11 @@ extern long double strtold (const char *__nptr, char **__endptr);
 # ifndef __GNUC__
 #  define strtold (long double)strtod
 #  define strtof (float)strtod
-#  ifdef _WIN64
+#  ifndef strtoll
 #   define strtoll _strtoi64
+#  endif
+#  ifndef strtoull
 #   define strtoull _strtoui64
-#  else
-#   define strtoll strtol
-#   define strtoull strtoul
 #  endif
 # endif
 # ifdef LIBTCC_AS_DLL
diff --git a/win32/include/stdlib.h b/win32/include/stdlib.h
index 033c0fdf..36e8b60d 100644
--- a/win32/include/stdlib.h
+++ b/win32/include/stdlib.h
@@ -536,7 +536,7 @@ extern "C" {
 #endif
 #endif
 
-#if !defined __NO_ISOCEXT /* externs in static libmingwex.a */
+#if !defined __NO_ISOCEXT
 
   typedef struct { long long quot, rem; } lldiv_t;
 
@@ -544,8 +544,18 @@ extern "C" {
 
   __CRT_INLINE long long __cdecl llabs(long long _j) { return (_j >= 0 ? _j : -_j); }
 
+  /* stro[u]ll do not properly map in Windows; use macros as VC++ does */
+ #if !defined(strtoll)
+  #define strtoll _strtoi64
+ #endif
+ #if !defined(strtoull)
+  #define strtoull _strtoui64
+ #endif
+
+/*
   long long  __cdecl strtoll(const char* __restrict__, char** __restrict, int);
   unsigned long long  __cdecl strtoull(const char* __restrict__, char** __restrict__, int);
+*/
 
   /* these are stubs for MS _i64 versions */
   long long  __cdecl atoll (const char *);