diff -r fcf4d547bed8 -r 6108f24fb1ad Include/pyport.h
--- a/Include/pyport.h	Sat Jan 21 20:27:59 2012 +0100
+++ b/Include/pyport.h	Fri Jan 27 15:37:09 2012 +0100
@@ -549,6 +549,16 @@
         _Py_set_387controlword(old_387controlword)
 #endif
 
+#ifdef HAVE_VC_FUNC_FOR_X87
+#define HAVE_PY_SET_53BIT_PRECISION 1
+#define _Py_SET_53BIT_PRECISION_HEADER                          \
+    unsigned short old_387controlword, new_387controlword
+#define _Py_SET_53BIT_PRECISION_START							\
+	_controlfp_s(&old_387controlword, _PC_53, _MCW_PC)    
+#define _Py_SET_53BIT_PRECISION_END                             \
+	_controlfp_s(&old_387controlword, old_387controlword, _MCW_PC)
+#endif
+
 /* default definitions are empty */
 #ifndef HAVE_PY_SET_53BIT_PRECISION
 #define _Py_SET_53BIT_PRECISION_HEADER
diff -r fcf4d547bed8 -r 6108f24fb1ad Objects/floatobject.c
--- a/Objects/floatobject.c	Sat Jan 21 20:27:59 2012 +0100
+++ b/Objects/floatobject.c	Fri Jan 27 15:37:09 2012 +0100
@@ -1087,6 +1087,8 @@
     int decpt, sign, val, halfway_case;
     PyObject *result = NULL;
 
+    _Py_SET_53BIT_PRECISION_HEADER;
+
     /* The basic idea is very simple: convert and round the double to a
        decimal string using _Py_dg_dtoa, then convert that decimal string
        back to a double with _Py_dg_strtod.  There's one minor difficulty:
@@ -1142,7 +1144,9 @@
         halfway_case = 0;
 
     /* round to a decimal string; use an extra place for halfway case */
+    _Py_SET_53BIT_PRECISION_START;
     buf = _Py_dg_dtoa(x, 3, ndigits+halfway_case, &decpt, &sign, &buf_end);
+    _Py_SET_53BIT_PRECISION_END;
     if (buf == NULL) {
         PyErr_NoMemory();
         return NULL;
@@ -1186,7 +1190,9 @@
 
     /* and convert the resulting string back to a double */
     errno = 0;
+    _Py_SET_53BIT_PRECISION_START;
     rounded = _Py_dg_strtod(mybuf, NULL);
+    _Py_SET_53BIT_PRECISION_END;
     if (errno == ERANGE && fabs(rounded) >= 1.)
         PyErr_SetString(PyExc_OverflowError,
                         "rounded value too large to represent");
diff -r fcf4d547bed8 -r 6108f24fb1ad PCbuild/pythoncore.vcproj
--- a/PCbuild/pythoncore.vcproj	Sat Jan 21 20:27:59 2012 +0100
+++ b/PCbuild/pythoncore.vcproj	Fri Jan 27 15:37:09 2012 +0100
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="Windows-1252"?>
 <VisualStudioProject
 	ProjectType="Visual C++"
-	Version="9,00"
+	Version="9.00"
 	Name="pythoncore"
 	ProjectGUID="{CF7AC3D1-E2DF-41D2-BEA6-1E2556CDEA26}"
 	RootNamespace="pythoncore"
@@ -44,7 +44,7 @@
 				Name="VCCLCompilerTool"
 				AdditionalOptions="/Zm200 "
 				AdditionalIncludeDirectories="..\Python;..\Modules\zlib"
-				PreprocessorDefinitions="_USRDLL;Py_BUILD_CORE;Py_ENABLE_SHARED;WIN32"
+				PreprocessorDefinitions="_USRDLL;Py_BUILD_CORE;Py_ENABLE_SHARED;WIN32;HAVE_VC_FUNC_FOR_X87"
 				RuntimeLibrary="2"
 			/>
 			<Tool
@@ -655,11 +655,11 @@
 				>
 			</File>
 			<File
-				RelativePath="..\Include\bytes_methods.h"
+				RelativePath="..\Include\bytearrayobject.h"
 				>
 			</File>
 			<File
-				RelativePath="..\Include\bytearrayobject.h"
+				RelativePath="..\Include\bytes_methods.h"
 				>
 			</File>
 			<File
@@ -1411,11 +1411,11 @@
 				>
 			</File>
 			<File
-				RelativePath="..\Objects\bytes_methods.c"
+				RelativePath="..\Objects\bytearrayobject.c"
 				>
 			</File>
 			<File
-				RelativePath="..\Objects\bytearrayobject.c"
+				RelativePath="..\Objects\bytes_methods.c"
 				>
 			</File>
 			<File