diff --git a/dlls/msvcp70/msvcp70.spec b/dlls/msvcp70/msvcp70.spec
index 749e64a30e9..7067efad88d 100644
--- a/dlls/msvcp70/msvcp70.spec
+++ b/dlls/msvcp70/msvcp70.spec
@@ -2103,9 +2103,9 @@
 @ stub ?_Isinf@?$_Ctraits@M@std@@SA_NM@Z
 @ stub ?_Isinf@?$_Ctraits@N@std@@SA_NN@Z
 @ stub ?_Isinf@?$_Ctraits@O@std@@SA_NO@Z
-@ stub ?_Isnan@?$_Ctraits@M@std@@SA_NM@Z
-@ stub ?_Isnan@?$_Ctraits@N@std@@SA_NN@Z
-@ stub ?_Isnan@?$_Ctraits@O@std@@SA_NO@Z
+@ cdecl ?_Isnan@?$_Ctraits@M@std@@SA_NM@Z(float) std_Ctraits_float__Isnan
+@ cdecl ?_Isnan@?$_Ctraits@N@std@@SA_NN@Z(double) std_Ctraits_double__Isnan
+@ cdecl ?_Isnan@?$_Ctraits@O@std@@SA_NO@Z(double) std_Ctraits_long_double__Isnan
 @ stub -arch=win32 ?_Loc_atexit@std@@YA_NP6AXXZ@Z
 @ stub -arch=win32 ?_Makpat@?$_Mpunct@D@std@@AAEXAAUpattern@money_base@2@III@Z
 @ stub -arch=win64 ?_Makpat@?$_Mpunct@D@std@@AEAAXAEAUpattern@money_base@2@III@Z
diff --git a/dlls/msvcp71/msvcp71.spec b/dlls/msvcp71/msvcp71.spec
index 1b56e177f35..0bac67cde51 100644
--- a/dlls/msvcp71/msvcp71.spec
+++ b/dlls/msvcp71/msvcp71.spec
@@ -2300,9 +2300,9 @@
 @ stub ?_Isinf@?$_Ctraits@M@std@@SA_NM@Z
 @ stub ?_Isinf@?$_Ctraits@N@std@@SA_NN@Z
 @ stub ?_Isinf@?$_Ctraits@O@std@@SA_NO@Z
-@ stub ?_Isnan@?$_Ctraits@M@std@@SA_NM@Z
-@ stub ?_Isnan@?$_Ctraits@N@std@@SA_NN@Z
-@ stub ?_Isnan@?$_Ctraits@O@std@@SA_NO@Z
+@ cdecl ?_Isnan@?$_Ctraits@M@std@@SA_NM@Z(float) std_Ctraits_float__Isnan
+@ cdecl ?_Isnan@?$_Ctraits@N@std@@SA_NN@Z(double) std_Ctraits_double__Isnan
+@ cdecl ?_Isnan@?$_Ctraits@O@std@@SA_NO@Z(double) std_Ctraits_long_double__Isnan
 @ thiscall -arch=win32 ?_Lock@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QAEXXZ(ptr) basic_streambuf_char__Lock
 @ cdecl -arch=win64 ?_Lock@?$basic_streambuf@DU?$char_traits@D@std@@@std@@QEAAXXZ(ptr) basic_streambuf_char__Lock
 @ thiscall -arch=win32 ?_Lock@?$basic_streambuf@GU?$char_traits@G@std@@@std@@QAEXXZ(ptr) basic_streambuf_wchar__Lock
diff --git a/dlls/msvcp80/msvcp80.spec b/dlls/msvcp80/msvcp80.spec
index 31e5e6014ea..11654911a2f 100644
--- a/dlls/msvcp80/msvcp80.spec
+++ b/dlls/msvcp80/msvcp80.spec
@@ -2557,9 +2557,9 @@
 @ stub ?_Isinf@?$_Ctraits@M@std@@SA_NM@Z
 @ stub ?_Isinf@?$_Ctraits@N@std@@SA_NN@Z
 @ stub ?_Isinf@?$_Ctraits@O@std@@SA_NO@Z
-@ stub ?_Isnan@?$_Ctraits@M@std@@SA_NM@Z
-@ stub ?_Isnan@?$_Ctraits@N@std@@SA_NN@Z
-@ stub ?_Isnan@?$_Ctraits@O@std@@SA_NO@Z
+@ cdecl ?_Isnan@?$_Ctraits@M@std@@SA_NM@Z(float) std_Ctraits_float__Isnan
+@ cdecl ?_Isnan@?$_Ctraits@N@std@@SA_NN@Z(double) std_Ctraits_double__Isnan
+@ cdecl ?_Isnan@?$_Ctraits@O@std@@SA_NO@Z(double) std_Ctraits_long_double__Isnan
 @ cdecl -arch=win32 ?_Locimp_Addfac@_Locimp@locale@std@@CAXPAV123@PAVfacet@23@I@Z(ptr ptr long) locale__Locimp__Locimp_Addfac
 @ cdecl -arch=win64 ?_Locimp_Addfac@_Locimp@locale@std@@CAXPEAV123@PEAVfacet@23@_K@Z(ptr ptr long) locale__Locimp__Locimp_Addfac
 @ cdecl -arch=win32 ?_Locimp_ctor@_Locimp@locale@std@@CAXPAV123@ABV123@@Z(ptr ptr) locale__Locimp__Locimp_ctor
diff --git a/dlls/msvcp90/math.c b/dlls/msvcp90/math.c
index 7ea6b698fe2..439865a197f 100644
--- a/dlls/msvcp90/math.c
+++ b/dlls/msvcp90/math.c
@@ -815,6 +815,15 @@ std_Ctraits * __thiscall std_Ctraits_op_assign( std_Ctraits *this, std_Ctraits *
     return this;
 }
 
+/* ?_Isnan@?$_Ctraits@M@std@@SA_NM@Z -> public: static bool __cdecl std::_Ctraits<float>::_Isnan(float) */
+BOOLEAN __cdecl std_Ctraits_float__Isnan( float x ) { return _isnan(x); }
+
+/* ?_Isnan@?$_Ctraits@N@std@@SA_NN@Z -> public: static bool __cdecl std::_Ctraits<double>::_Isnan(double) */
+BOOLEAN __cdecl std_Ctraits_double__Isnan( double x ) { return _isnan(x); }
+
+/* ?_Isnan@?$_Ctraits@O@std@@SA_NO@Z -> public: static bool __cdecl std::_Ctraits<long double>::_Isnan(long double) */
+BOOLEAN __cdecl std_Ctraits_long_double__Isnan( LDOUBLE x ) { return _isnan(x); }
+
 /* ?atan2@?$_Ctraits@M@std@@SAMMM@Z -> public: static float __cdecl std::_Ctraits<float>::atan2(float,float) */
 float __cdecl std_Ctraits_float_atan2( float y, float x ) { return atan2f( y, x ); }
 
diff --git a/dlls/msvcp90/msvcp90.spec b/dlls/msvcp90/msvcp90.spec
index 52717370afc..edb984b2b51 100644
--- a/dlls/msvcp90/msvcp90.spec
+++ b/dlls/msvcp90/msvcp90.spec
@@ -2878,9 +2878,9 @@
 @ stub ?_Isinf@?$_Ctraits@M@std@@SA_NM@Z
 @ stub ?_Isinf@?$_Ctraits@N@std@@SA_NN@Z
 @ stub ?_Isinf@?$_Ctraits@O@std@@SA_NO@Z
-@ stub ?_Isnan@?$_Ctraits@M@std@@SA_NM@Z
-@ stub ?_Isnan@?$_Ctraits@N@std@@SA_NN@Z
-@ stub ?_Isnan@?$_Ctraits@O@std@@SA_NO@Z
+@ cdecl ?_Isnan@?$_Ctraits@M@std@@SA_NM@Z(float) std_Ctraits_float__Isnan
+@ cdecl ?_Isnan@?$_Ctraits@N@std@@SA_NN@Z(double) std_Ctraits_double__Isnan
+@ cdecl ?_Isnan@?$_Ctraits@O@std@@SA_NO@Z(double) std_Ctraits_long_double__Isnan
 @ cdecl -arch=win32 ?_Locimp_Addfac@_Locimp@locale@std@@CAXPAV123@PAVfacet@23@I@Z(ptr ptr long) locale__Locimp__Locimp_Addfac
 @ cdecl -arch=win64 ?_Locimp_Addfac@_Locimp@locale@std@@CAXPEAV123@PEAVfacet@23@_K@Z(ptr ptr long) locale__Locimp__Locimp_Addfac
 @ cdecl -arch=win32 ?_Locimp_ctor@_Locimp@locale@std@@CAXPAV123@ABV123@@Z(ptr ptr) locale__Locimp__Locimp_ctor
diff --git a/dlls/msvcp90/tests/misc.c b/dlls/msvcp90/tests/misc.c
index 26cafc95d9d..a4e07d7dabf 100644
--- a/dlls/msvcp90/tests/misc.c
+++ b/dlls/msvcp90/tests/misc.c
@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include <locale.h>
 #include <wctype.h>
+#include <math.h>
 #include <float.h>
 #include <errno.h>
 
@@ -26,6 +27,8 @@
 #include <winbase.h>
 #include "wine/test.h"
 
+typedef double LDOUBLE;  /* long double is just a double */
+
 typedef struct {
     LCID handle;
     unsigned page;
@@ -110,6 +113,10 @@ static void (__thiscall *p_basic_ostringstream_char_dtor)(/*basic_ostringstream_
 static void (__thiscall *p_basic_ostringstream_char_vbase_dtor)(/*basic_ostringstream_char*/void*);
 static void (__thiscall *p_basic_ios_char_dtor)(/*basic_ios_char*/void*);
 
+static BOOL (__cdecl *p_std_Ctraits_float__Isnan)(float);
+static BOOL (__cdecl *p_std_Ctraits_double__Isnan)(double);
+static BOOL (__cdecl *p_std_Ctraits_long_double__Isnan)(LDOUBLE);
+
 static complex_float* (__thiscall *p_complex_float_ctor)(complex_float*, const float*, const float*);
 static complex_float* (__cdecl *p_complex_float_add)(complex_float*, const complex_float*, const complex_float*);
 static complex_float* (__cdecl *p_complex_float_div)(complex_float*, const complex_float*, const complex_float*);
@@ -216,6 +223,11 @@ static BOOL init(void)
     SET(p_wctrans, "wctrans");
     SET(p_towctrans, "towctrans");
     SET(basic_ostringstream_char_vbtable, "??_8?$basic_ostringstream@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@7B@");
+
+    SET(p_std_Ctraits_float__Isnan, "?_Isnan@?$_Ctraits@M@std@@SA_NM@Z");
+    SET(p_std_Ctraits_double__Isnan, "?_Isnan@?$_Ctraits@N@std@@SA_NN@Z");
+    SET(p_std_Ctraits_long_double__Isnan, "?_Isnan@?$_Ctraits@O@std@@SA_NO@Z");
+
     if(sizeof(void*) == 8) { /* 64-bit initialization */
         SET(p_char_assign, "?assign@?$char_traits@D@std@@SAXAEADAEBD@Z");
         SET(p_wchar_assign, "?assign@?$char_traits@_W@std@@SAXAEA_WAEB_W@Z");
@@ -688,6 +700,41 @@ static BOOL almost_eq(float f1, float f2)
     return f1 < 0.0001;
 }
 
+static void test_Ctraits_math_functions(void)
+{
+    BYTE ret;
+
+    ret = p_std_Ctraits_float__Isnan(0.0);
+    ok(ret == FALSE, "ret = %d\n", ret);
+
+    ret = p_std_Ctraits_float__Isnan(0.0 / 0.0);
+    ok(ret == TRUE, "ret = %d\n", ret);
+
+    ret = p_std_Ctraits_float__Isnan(1.0 / 0.0);
+    ok(ret == FALSE, "ret = %d\n", ret);
+
+    ret = p_std_Ctraits_float__Isnan(-1.0 / 0.0);
+    ok(ret == FALSE, "ret = %d\n", ret);
+
+    ret = p_std_Ctraits_float__Isnan(log(-1.0));
+    ok(ret == TRUE, "ret = %d\n", ret);
+
+    ret = p_std_Ctraits_float__Isnan(sqrt(-1.0));
+    ok(ret == TRUE, "ret = %d\n", ret);
+
+    ret = p_std_Ctraits_double__Isnan(3.14159 / 0.0);
+    ok(ret == FALSE, "ret = %d\n", ret);
+
+    ret = p_std_Ctraits_double__Isnan(log(-3.14159));
+    ok(ret == TRUE, "ret = %d\n", ret);
+
+    ret = p_std_Ctraits_long_double__Isnan(3.14159 / 0.0);
+    ok(ret == FALSE, "ret = %d\n", ret);
+
+    ret = p_std_Ctraits_long_double__Isnan(sqrt(-3.14159));
+    ok(ret == TRUE, "ret = %d\n", ret);
+}
+
 static void test_complex(void)
 {
     complex_float c1, c2, c3;
@@ -935,6 +982,7 @@ START_TEST(misc)
     test_virtual_call();
     test_virtual_base_dtors();
     test_allocator_char();
+    test_Ctraits_math_functions();
     test_complex();
 
     ok(!invalid_parameter, "invalid_parameter_handler was invoked too many times\n");