diff --git a/PC/config.c b/PC/config.c
index f2d38ae..816edca 100644
--- a/PC/config.c
+++ b/PC/config.c
@@ -52,6 +52,7 @@
 extern void init_winreg(void);
 extern void init_struct(void);
 extern void initdatetime(void);
+extern void init_fileio(void);
 extern void init_functools(void);
 extern void initzlib(void);
 
@@ -129,6 +130,7 @@
 	{"_winreg", init_winreg},
 	{"_struct", init_struct},
 	{"datetime", initdatetime},
+	{"_fileio", init_fileio},
 	{"_functools", init_functools},
 
 	{"xxsubtype", initxxsubtype},
diff --git a/PC/pyconfig.h b/PC/pyconfig.h
index 1892cf1..7cba340 100644
--- a/PC/pyconfig.h
+++ b/PC/pyconfig.h
@@ -207,12 +207,13 @@
 #endif /* MS_WIN32 && !MS_WIN64 */
 
 typedef int pid_t;
-#define hypot _hypot
 
 #include <float.h>
 #define Py_IS_NAN _isnan
 #define Py_IS_INFINITY(X) (!_finite(X) && !_isnan(X))
 #define Py_IS_FINITE(X) _finite(X)
+#define copysign _copysign
+#define hypot _hypot
 
 #endif /* _MSC_VER */
 
@@ -392,7 +393,7 @@
 /* Fairly standard from here! */
 
 /* Define to 1 if you have the `copysign' function. */
-/* #define HAVE_COPYSIGN 1*/
+#define HAVE_COPYSIGN 1
 
 /* Define to 1 if you have the `isinf' function. */
 #define HAVE_ISINF 1
diff --git a/PCbuild/pythoncore.vcproj b/PCbuild/pythoncore.vcproj
index b02703a..3d3601a 100644
--- a/PCbuild/pythoncore.vcproj
+++ b/PCbuild/pythoncore.vcproj
@@ -987,6 +987,10 @@
 				>
 			</File>
 			<File
+				RelativePath="..\Modules\_fileio.c"
+				>
+			</File>
+			<File
 				RelativePath="..\Modules\_functoolsmodule.c"
 				>
 			</File>