4 files changed, 23 insertions, 2 deletions
diff --git a/src/include/c.h b/src/include/c.h
index 634b21fa949..af1be9499ef 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -58,7 +58,7 @@
 #endif
 #include "postgres_ext.h"
 
-#if _MSC_VER >= 1400
+#if _MSC_VER >= 1400 || defined(WIN64)
 #define errcode __msvc_errcode
 #include <crtdefs.h>
 #undef errcode
diff --git a/src/include/port.h b/src/include/port.h
index 7ad464c07dc..4d40cef7b4b 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -325,8 +325,12 @@ extern FILE *pgwin32_fopen(const char *, const char *);
 #define		fopen(a,b) pgwin32_fopen(a,b)
 #endif
 
+#ifndef popen
 #define popen(a,b) _popen(a,b)
+#endif
+#ifndef pclose
 #define pclose(a) _pclose(a)
+#endif
 
 /* New versions of MingW have gettimeofday, old mingw and msvc don't */
 #ifndef HAVE_GETTIMEOFDAY
diff --git a/src/include/port/win32.h b/src/include/port/win32.h
index 93439f763d0..6d99ecbe88d 100644
--- a/src/include/port/win32.h
+++ b/src/include/port/win32.h
@@ -4,7 +4,16 @@
 #define WIN32_ONLY_COMPILER
 #endif
 
+/* 
+ * Make sure _WIN32_WINNT has the minumum required value. 
+ * Leave a higher value in place.
+*/
+#if defined(_WIN32_WINNT) && _WIN32_WINNT < 0x0501
+#undefine _WIN32_WINNT
+#endif
+#ifndef _WIN32_WINNT
 #define _WIN32_WINNT 0x0501
+#endif
 /*
  * Always build with SSPI support. Keep it as a #define in case
  * we want a switch to disable it sometime in the future.
@@ -17,10 +26,17 @@
 #undef mkdir
 
 #undef ERROR
+
+/* 
+ * The Mingw64 headers choke if this is already defined - they
+ * define it themselves.
+ */
+#if !defined(WIN64) || defined(WIN32_ONLY_COMPILER)
 #define _WINSOCKAPI_
-#include <windows.h>
+#endif
 #include <winsock2.h>
 #include <ws2tcpip.h>
+#include <windows.h>
 #undef small
 #include <process.h>
 #include <signal.h>
diff --git a/src/include/port/win32/sys/socket.h b/src/include/port/win32/sys/socket.h
index 6947ec07d62..edaee6a894c 100644
--- a/src/include/port/win32/sys/socket.h
+++ b/src/include/port/win32/sys/socket.h
@@ -13,6 +13,7 @@
  */
 #include <winsock2.h>
 #include <ws2tcpip.h>
+#include <windows.h>
 
 #undef ERROR
 #undef small