diff --git a/dlls/d3dx9_36/tests/effect.c b/dlls/d3dx9_36/tests/effect.c
index c10decc5c2d..5c4a3c5e770 100644
--- a/dlls/d3dx9_36/tests/effect.c
+++ b/dlls/d3dx9_36/tests/effect.c
@@ -22,25 +22,6 @@
 #include "wine/test.h"
 #include "d3dx9.h"
 
-#ifndef INFINITY
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-#endif /* INFINITY */
-
-#ifndef NAN
-static float get_nan(void)
-{
-    DWORD nan = 0x7fc00000;
-
-    return *(float *)&nan;
-}
-#define NAN get_nan()
-#endif
-
 /* helper functions */
 static BOOL compare_float(FLOAT f, FLOAT g, UINT ulps)
 {
diff --git a/dlls/msvcirt/tests/msvcirt.c b/dlls/msvcirt/tests/msvcirt.c
index c856b50a418..2cdd10d279c 100644
--- a/dlls/msvcirt/tests/msvcirt.c
+++ b/dlls/msvcirt/tests/msvcirt.c
@@ -18,6 +18,7 @@
 
 #include <fcntl.h>
 #include <float.h>
+#include <math.h>
 #include <io.h>
 #include <stdio.h>
 #include <windef.h>
@@ -180,20 +181,6 @@ typedef struct {
     exception e;
 } logic_error;
 
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-
-static inline float __port_nan(void)
-{
-    static const unsigned __nan_bytes = 0x7fc00000;
-    return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-
 #undef __thiscall
 #ifdef __i386__
 #define __thiscall __stdcall
diff --git a/dlls/msvcp120/tests/msvcp120.c b/dlls/msvcp120/tests/msvcp120.c
index c416a1020b7..8f7b75aab4b 100644
--- a/dlls/msvcp120/tests/msvcp120.c
+++ b/dlls/msvcp120/tests/msvcp120.c
@@ -169,20 +169,6 @@ static void init_thiscall_thunk(void)
 #define call_func7(func,_this,a,b,c,d,e,f) func(_this,a,b,c,d,e,f)
 #endif /* __i386__ */
 
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-
-static inline float __port_nan(void)
-{
-    static const unsigned __nan_bytes = 0x7fc00000;
-    return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-
 typedef int MSVCRT_long;
 typedef unsigned char MSVCP_bool;
 
diff --git a/dlls/msvcp90/tests/misc.c b/dlls/msvcp90/tests/misc.c
index e9fd1e06be7..34a533a0a54 100644
--- a/dlls/msvcp90/tests/misc.c
+++ b/dlls/msvcp90/tests/misc.c
@@ -27,20 +27,6 @@
 #include <winbase.h>
 #include "wine/test.h"
 
-static inline float __port_infinity(void)
-{
-        static const unsigned __inf_bytes = 0x7f800000;
-            return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-
-static inline float __port_nan(void)
-{
-        static const unsigned __nan_bytes = 0x7fc00000;
-            return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-
 static inline float __port_ind(void)
 {
         static const unsigned __ind_bytes = 0xffc00000;
diff --git a/dlls/msvcr120/tests/msvcr120.c b/dlls/msvcr120/tests/msvcr120.c
index be5df27e937..a055feeac91 100644
--- a/dlls/msvcr120/tests/msvcr120.c
+++ b/dlls/msvcr120/tests/msvcr120.c
@@ -22,6 +22,7 @@
 #include <wchar.h>
 #include <stdio.h>
 #include <float.h>
+#include <math.h>
 #include <limits.h>
 #include <wctype.h>
 
@@ -114,30 +115,6 @@ typedef struct {
     critical_section lock;
 } _Condition_variable;
 
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-
-static inline float __port_nan(void)
-{
-    static const unsigned __nan_bytes = 0x7fc00000;
-    return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-
-static inline int isnormal(double d)
-{
-    return _fpclass(d) & (_FPCLASS_PN | _FPCLASS_NN);
-}
-
-static inline int isinf(double d)
-{
-    return _fpclass(d) & (_FPCLASS_PINF | _FPCLASS_NINF);
-}
-
 struct MSVCRT_lconv
 {
     char* decimal_point;
diff --git a/dlls/msvcrt/tests/misc.c b/dlls/msvcrt/tests/misc.c
index c170d232250..c59464f82d6 100644
--- a/dlls/msvcrt/tests/misc.c
+++ b/dlls/msvcrt/tests/misc.c
@@ -25,20 +25,6 @@
 #include "msvcrt.h"
 #include <process.h>
 
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-
-static inline float __port_nan(void)
-{
-    static const unsigned __nan_bytes = 0x7fc00000;
-    return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-
 static inline BOOL almost_equal(double d1, double d2) {
     if(d1-d2>-1e-30 && d1-d2<1e-30)
         return TRUE;
diff --git a/dlls/msvcrt/tests/printf.c b/dlls/msvcrt/tests/printf.c
index ad55e4f604b..5e15989d1cf 100644
--- a/dlls/msvcrt/tests/printf.c
+++ b/dlls/msvcrt/tests/printf.c
@@ -24,9 +24,10 @@
  * the following macro is defined.
  */
 #define _CRT_NON_CONFORMING_SWPRINTFS
- 
+
 #include <stdio.h>
 #include <errno.h>
+#include <math.h>
 #include <locale.h>
 
 #include "windef.h"
@@ -35,20 +36,6 @@
 
 #include "wine/test.h"
 
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-
-static inline float __port_nan(void)
-{
-    static const unsigned __nan_bytes = 0x7fc00000;
-    return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-
 static inline float __port_ind(void)
 {
     static const unsigned __ind_bytes = 0xffc00000;
diff --git a/dlls/ucrtbase/tests/misc.c b/dlls/ucrtbase/tests/misc.c
index 7559edecc33..4da6abff73e 100644
--- a/dlls/ucrtbase/tests/misc.c
+++ b/dlls/ucrtbase/tests/misc.c
@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <wchar.h>
 #include <stdio.h>
+#include <math.h>
 #include <float.h>
 #include <io.h>
 #include <sys/stat.h>
@@ -57,20 +58,6 @@
         expect_ ## func = called_ ## func = FALSE; \
     }while(0)
 
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-
-static inline float __port_nan(void)
-{
-    static const unsigned __nan_bytes = 0x7fc00000;
-    return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-
 static inline double __port_min_pos_double(void)
 {
     static const UINT64 __min_pos_double = 0x10000000000000;
diff --git a/dlls/ucrtbase/tests/printf.c b/dlls/ucrtbase/tests/printf.c
index 41bb6a335ed..769121ebd98 100644
--- a/dlls/ucrtbase/tests/printf.c
+++ b/dlls/ucrtbase/tests/printf.c
@@ -23,6 +23,7 @@
 
 #include <stdio.h>
 #include <errno.h>
+#include <math.h>
 
 #include "windef.h"
 #include "winbase.h"
@@ -66,20 +67,6 @@ DEFINE_EXPECT(invalid_parameter_handler);
 #define UCRTBASE_PRINTF_LEGACY_MSVCRT_COMPATIBILITY      (0x0008)
 #define UCRTBASE_PRINTF_LEGACY_THREE_DIGIT_EXPONENTS     (0x0010)
 
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-
-static inline float __port_nan(void)
-{
-    static const unsigned __nan_bytes = 0x7fc00000;
-    return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-
 static inline float __port_ind(void)
 {
     static const unsigned __ind_bytes = 0xffc00000;
diff --git a/dlls/ucrtbase/tests/string.c b/dlls/ucrtbase/tests/string.c
index 38aa6b3fa3c..e96843125e6 100644
--- a/dlls/ucrtbase/tests/string.c
+++ b/dlls/ucrtbase/tests/string.c
@@ -57,24 +57,6 @@ DEFINE_EXPECT(invalid_parameter_handler);
 
 static _invalid_parameter_handler (__cdecl *p_set_invalid_parameter_handler)(_invalid_parameter_handler);
 
-#ifndef INFINITY
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-#endif
-
-#ifndef NAN
-static inline float __port_nan(void)
-{
-    static const unsigned __nan_bytes = 0x7fc00000;
-    return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-#endif
-
 static void __cdecl test_invalid_parameter_handler(const wchar_t *expression,
         const wchar_t *function, const wchar_t *file,
         unsigned line, uintptr_t arg)
diff --git a/dlls/webservices/tests/writer.c b/dlls/webservices/tests/writer.c
index 8d189fd9e4e..905f397b64b 100644
--- a/dlls/webservices/tests/writer.c
+++ b/dlls/webservices/tests/writer.c
@@ -17,30 +17,12 @@
  */
 
 #include <stdio.h>
+#include <math.h>
 #include "windows.h"
 #include "rpc.h"
 #include "webservices.h"
 #include "wine/test.h"
 
-#include <math.h>
-#ifndef INFINITY
-static inline float __port_infinity(void)
-{
-    static const unsigned __inf_bytes = 0x7f800000;
-    return *(const float *)&__inf_bytes;
-}
-#define INFINITY __port_infinity()
-#endif
-
-#ifndef NAN
-static inline float __port_nan(void)
-{
-    static const unsigned __nan_bytes = 0x7fc00000;
-    return *(const float *)&__nan_bytes;
-}
-#define NAN __port_nan()
-#endif
-
 static HRESULT set_output( WS_XML_WRITER *writer )
 {
     WS_XML_WRITER_TEXT_ENCODING text = { {WS_XML_WRITER_ENCODING_TYPE_TEXT}, WS_CHARSET_UTF8 };
diff --git a/include/msvcrt/math.h b/include/msvcrt/math.h
index b82961e817c..e85767926f4 100644
--- a/include/msvcrt/math.h
+++ b/include/msvcrt/math.h
@@ -205,6 +205,18 @@ static const union {
 #  endif
 #endif
 
+#if defined(__GNUC__) && ((__GNUC__ > 3) || ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 3)))
+# define INFINITY __builtin_inff()
+# define NAN      __builtin_nanf("")
+#else
+static const union {
+    unsigned int __i;
+    float __f;
+} __inff = { 0x7f800000 }, __nanf = { 0x7fc00000 };
+# define INFINITY (__inff.__f)
+# define NAN      (__nanf.__f)
+#endif
+
 #define FP_INFINITE   1
 #define FP_NAN        2
 #define FP_NORMAL    -1
diff --git a/include/wine/test.h b/include/wine/test.h
index 0797204a50e..b5aa9c14c70 100644
--- a/include/wine/test.h
+++ b/include/wine/test.h
@@ -46,6 +46,15 @@
 #define INVALID_SET_FILE_POINTER (~0u)
 #endif
 
+#ifdef _MSC_VER
+# ifndef INFINITY
+#  define INFINITY ((float)HUGE_VAL)
+# endif
+# ifndef NAN
+#  define NAN (INFINITY * 0.0f)
+# endif
+#endif
+
 /* debug level */
 extern int winetest_debug;