diff -r 41cabdff2686 -r c6d3b5af7d74 Include/pyport.h
--- a/Include/pyport.h	Fri Feb 03 02:39:49 2012 +0100
+++ b/Include/pyport.h	Mon Feb 06 23:51:58 2012 +0100
@@ -549,6 +549,30 @@
         _Py_set_387controlword(old_387controlword)
 #endif
 
+/* get and set x87 control word for MS VC /x86 */
+#ifdef _MSC_VER
+#ifdef _WIN32
+/* x87 not supported in 64bit applications */
+#ifndef _WIN64
+#define HAVE_PY_SET_53BIT_PRECISION 1
+#define _Py_SET_53BIT_PRECISION_HEADER                          \
+    unsigned int old_387controlword, new_387controlword
+/* we are using the __control87_2 function to set only the x87 controlword.
+   SSE controlword is unaffected  */
+#define _Py_SET_53BIT_PRECISION_START                           \
+    do {                                                        \
+        __control87_2(0, 0, &old_387controlword, NULL);         \
+        if ((old_387controlword & (_MCW_PC | _MCW_RC)) != _PC_53) \
+            __control87_2(_PC_53, _MCW_PC | _MCW_RC, &new_387controlword, NULL); \
+    } while (0)
+#define _Py_SET_53BIT_PRECISION_END                             \
+    if (new_387controlword != old_387controlword)               \
+        __control87_2(old_387controlword, _MCW_PC | _MCW_RC,    \
+                        &new_387controlword, NULL)
+#endif
+#endif
+#endif
+
 /* default definitions are empty */
 #ifndef HAVE_PY_SET_53BIT_PRECISION
 #define _Py_SET_53BIT_PRECISION_HEADER