diff --git a/sc2/build.vars.in b/sc2/build.vars.in
index 25b8a178d..3a774a7d8 100644
--- a/sc2/build.vars.in
+++ b/sc2/build.vars.in
@@ -41,5 +41,6 @@ uqm_USE_PLATFORM_ACCEL='@USE_PLATFORM_ACCEL@'
 uqm_NETPLAY='@NETPLAY@'
 DEBUG='@DEBUG@'
 export BUILD_SYSTEM HOST_SYSTEM DEBUG
+export MACRO_WIN32 MACRO__MCS_VER MACRO___MINGW32__
 export uqm_SOUNDMODULE uqm_USE_INTERNAL_MIKMOD uqm_HAVE_REGEX
 export uqm_HAVE_OPENGL uqm_USE_ZIP_IO uqm_USE_PLATFORM_ACCEL uqm_NETPLAY
diff --git a/sc2/build/unix/build.config b/sc2/build/unix/build.config
index faf8f72fd..ae2b07584 100644
--- a/sc2/build/unix/build.config
+++ b/sc2/build/unix/build.config
@@ -48,6 +48,12 @@ uqm_requirements()
 	# Add defines for HAVE_GETOPT_LONG and HAVE_REGEX_H
 	define_have_symbol getopt_long
 	define_have_header regex.h
+
+	# Add an environment variable for MACRO_WIN32, MACRO__MCS_VER, and
+	# MACRO___MINGW32__
+	define_have_macro WIN32
+	define_have_macro _MCS_VER
+	define_have_macro __MINGW32__
 }
 
 uqm_prepare_config()
diff --git a/sc2/build/unix/config_functions b/sc2/build/unix/config_functions
index a0a0e9dc4..aa7277015 100644
--- a/sc2/build/unix/config_functions
+++ b/sc2/build/unix/config_functions
@@ -538,7 +538,7 @@ EOF
 }
 
 # Description: check if a symbol is defined.
-#              set HAVE_<NAME> accordingly, where <NAME> is the capitalized
+#              sets HAVE_<NAME> accordingly, where <NAME> is the capitalized
 #              name of the symbol.
 # Arguments:   $1 - the name of the symbol
 define_have_symbol() {
@@ -600,9 +600,9 @@ EOF
 }
 
 # Description: check if a header is available.
-#              set HAVE_<NAME> accordingly, where <NAME> is the capitalized
+#              sets HAVE_<NAME> accordingly, where <NAME> is the capitalized
 #              name of the header file. "sys/time.h" becomes "SYS_TIME_H".
-# Arguments:   $1 - the name of the symbol
+# Arguments:   $1 - the name of the header file
 define_have_header() {
 	local NAME VALUE
 	NAME=`$TR /.[:lower:] __[:upper:] << EOF
@@ -618,6 +618,48 @@ EOF
 	fi
 }
 
+# Description: check if a macro is available.
+# Arguments:   $1 - the name of the macro
+have_macro() {
+	local MACRO EXTRA
+	MACRO="$1"
+
+	EXTRA=`evalVar MACRO_${NAME}_EXTRA`
+
+	try_compile_c "$TEMP_CFLAGS" "$TEMP_LDFLAGS" << EOF > /dev/null 2>&1
+$EXTRA
+#ifndef $MACRO
+#	error
+#endif
+int main() {
+	return 0;
+}
+EOF
+	if [ $? -gt 0 ]; then
+		build_message "Preprocessor macro '$MACRO' not found."
+		return 1
+	fi
+	build_message "Preprocessor macro '$MACRO' found."
+	return 0
+}
+
+# Description: check if a macro is defined
+#              sets MACRO_<NAME> to a non-empty string if the macro with
+#              the specified name is defined, and to an empty string if it
+#              is not.
+# Arguments:   $1 - the name of the symbol
+define_have_macro() {
+	local NAME
+
+	NAME=$1
+
+	if have_macro "$1"; then
+		add_symbol "MACRO_$NAME" "1"
+	else
+		add_symbol "MACRO_$NAME" ""
+	fi
+}
+
 # Description: Add a symbol to be replaced by substitute_vars
 #              $HAVE_SYMBOLS will contain the variable names of all
 #              symbols added by define_have_symbol and should be passed to
diff --git a/sc2/src/port.h b/sc2/src/port.h
index 53fc7bf94..ef98ff0b6 100644
--- a/sc2/src/port.h
+++ b/sc2/src/port.h
@@ -128,9 +128,13 @@ typedef unsigned short wchar_t;
 typedef unsigned int wint_t;
 #endif
 
+#if defined (_MSC_VER) || defined(__MINGW32__)
+#	define USE_WINSOCK
+#endif
+
 // errno error numbers. The values used don't matter, as long as they
 // don't conflict with existing errno error numbers.
-#if defined (PORT_WANT_ERRNO) && defined (_MSC_VER)
+#if defined (PORT_WANT_ERRNO) && defined (USE_WINSOCK)
 #	include <errno.h>
 #	ifndef E2BIG
 #		define E2BIG            0x01000001
diff --git a/sc2/src/sc2code/libs/network/Makeinfo b/sc2/src/sc2code/libs/network/Makeinfo
index 916fe848e..208974911 100644
--- a/sc2/src/sc2code/libs/network/Makeinfo
+++ b/sc2/src/sc2code/libs/network/Makeinfo
@@ -1,3 +1,8 @@
 uqm_SUBDIRS="connect netmanager socket"
-uqm_CFILES="netport.c network_bsd.c"
+uqm_CFILES="netport.c"
+if [ -n "$MACRO___MINGW32__" ]; then
+	uqm_CFILES="$uqm_CFILES network_win.c"
+else
+	uqm_CFILES="$uqm_CFILES network_bsd.c"
+fi
 
diff --git a/sc2/src/sc2code/libs/network/connect/connect.c b/sc2/src/sc2code/libs/network/connect/connect.c
index 6ca17c9a3..482b4dfc3 100644
--- a/sc2/src/sc2code/libs/network/connect/connect.c
+++ b/sc2/src/sc2code/libs/network/connect/connect.c
@@ -33,7 +33,7 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <string.h>
-#ifdef _MSC_VER
+#ifdef USE_WINSOCK
 #	include <winsock2.h>
 #	include <ws2tcpip.h>
 #	include <wspiapi.h>
diff --git a/sc2/src/sc2code/libs/network/connect/listen.c b/sc2/src/sc2code/libs/network/connect/listen.c
index c03beaeaf..78c75740f 100644
--- a/sc2/src/sc2code/libs/network/connect/listen.c
+++ b/sc2/src/sc2code/libs/network/connect/listen.c
@@ -32,14 +32,14 @@
 
 #include <assert.h>
 #include <errno.h>
-#ifdef _MSC_VER
+#ifdef USE_WINSOCK
 #	include <winsock2.h>
 #	include <ws2tcpip.h>
 #else
 #	include <netdb.h>
 #endif
 #ifdef DEBUG
-#	ifdef _MSC_VER
+#	ifdef USE_WINSOCK
 #		include <wspiapi.h>
 #	endif
 #endif
diff --git a/sc2/src/sc2code/libs/network/connect/listen.h b/sc2/src/sc2code/libs/network/connect/listen.h
index 59a8dc49c..d9ef85399 100644
--- a/sc2/src/sc2code/libs/network/connect/listen.h
+++ b/sc2/src/sc2code/libs/network/connect/listen.h
@@ -28,7 +28,9 @@ typedef enum {
 typedef struct ListenError ListenError;
 typedef struct ListenState ListenState;
 
-#ifdef _MSC_VER
+#include "port.h"
+
+#ifdef USE_WINSOCK
 // I do not want to include winsock2.h, because of possible conflicts with
 // code that includes this file.
 // Note that listen.c itself includes winsock2.h; SOCKLEN_T is used there
diff --git a/sc2/src/sc2code/libs/network/connect/resolve.h b/sc2/src/sc2code/libs/network/connect/resolve.h
index 131976d33..9702acaf0 100644
--- a/sc2/src/sc2code/libs/network/connect/resolve.h
+++ b/sc2/src/sc2code/libs/network/connect/resolve.h
@@ -28,9 +28,10 @@ typedef enum {
 } ResolveStateState;
 typedef struct ResolveState ResolveState;
 
+#include "port.h"
 
 // For addrinfo.
-#ifdef _MSC_VER
+#ifdef USE_WINSOCK
 // Not including <winsock2.h> because of possible conflicts with files
 // including this file.
 struct addrinfo;
@@ -63,13 +64,13 @@ typedef void (*ResolveErrorCallback)(ResolveState *resolveState,
 		const ResolveError *error);
 
 #ifdef RESOLVE_INTERNAL
-#ifdef _MSC_VER
+#ifdef USE_WINSOCK
 #	include <winsock2.h>
 #	include <ws2tcpip.h>
 #	include <wspiapi.h>
-#else  /* !defined(_MSC_VER) */
+#else  /* !defined(USE_WINSOCK) */
 #	include <netdb.h>
-#endif /* !defined(_MSC_VER) */
+#endif /* !defined(USE_WINSOCK) */
 
 struct ResolveState {
 	RefCount refCount;
diff --git a/sc2/src/sc2code/libs/network/netmanager/Makeinfo b/sc2/src/sc2code/libs/network/netmanager/Makeinfo
index 0accccfbb..7fb4fa8dc 100644
--- a/sc2/src/sc2code/libs/network/netmanager/Makeinfo
+++ b/sc2/src/sc2code/libs/network/netmanager/Makeinfo
@@ -1,2 +1,8 @@
-uqm_CFILES="ndesc.c netmanager_bsd.c"
+uqm_CFILES="ndesc.c"
+if [ -n "$MACRO___MINGW32__" ]; then
+	uqm_CFILES="$uqm_CFILES netmanager_win.c"
+else
+	uqm_CFILES="$uqm_CFILES netmanager_bsd.c"
+fi
+
 
diff --git a/sc2/src/sc2code/libs/network/netmanager/netmanager.h b/sc2/src/sc2code/libs/network/netmanager/netmanager.h
index 41d15562d..a3213686c 100644
--- a/sc2/src/sc2code/libs/network/netmanager/netmanager.h
+++ b/sc2/src/sc2code/libs/network/netmanager/netmanager.h
@@ -19,9 +19,10 @@
 #ifndef _NETMANAGER_H
 #define _NETMANAGER_H
 
+#include "port.h"
 #include "types.h"
 
-#ifdef WIN32
+#ifdef USE_WINSOCK
 #	include "netmanager_win.h"
 #else
 #	include "netmanager_bsd.h"
diff --git a/sc2/src/sc2code/libs/network/netport.c b/sc2/src/sc2code/libs/network/netport.c
index f205bb35b..bfd478c2b 100644
--- a/sc2/src/sc2code/libs/network/netport.c
+++ b/sc2/src/sc2code/libs/network/netport.c
@@ -20,7 +20,7 @@
 #include "port.h"
 #include "netport.h"
 
-#ifdef _MSC_VER
+#ifdef USE_WINSOCK
 #	include <winsock2.h>
 
 int
@@ -87,5 +87,5 @@ int
 getWinsockErrno(void) {
 	return winsockErrorToErrno(WSAGetLastError());
 }
-#endif  /* defined (_MSC_VER) */
+#endif  /* defined (USE_WINSOCK) */
 
diff --git a/sc2/src/sc2code/libs/network/netport.h b/sc2/src/sc2code/libs/network/netport.h
index 86ed6a1db..ce4899f3f 100644
--- a/sc2/src/sc2code/libs/network/netport.h
+++ b/sc2/src/sc2code/libs/network/netport.h
@@ -19,7 +19,9 @@
 #ifndef _NETPORT_H
 #define _NETPORT_H
 
-#if defined (_MSC_VER)
+#include "port.h"
+
+#if defined (USE_WINSOCK)
 int winsockErrorToErrno(int winsockError);
 int getWinsockErrno(void);
 #	define EAI_SYSTEM 0x02000001
diff --git a/sc2/src/sc2code/libs/network/socket/socket.c b/sc2/src/sc2code/libs/network/socket/socket.c
index deee918ad..be7d6015c 100644
--- a/sc2/src/sc2code/libs/network/socket/socket.c
+++ b/sc2/src/sc2code/libs/network/socket/socket.c
@@ -16,10 +16,12 @@
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include "port.h"
+
 #define SOCKET_INTERNAL
 #include "socket.h"
 
-#ifdef _MSC_VER
+#ifdef USE_WINSOCK
 #	include <winsock2.h>
 #else
 #	include <sys/socket.h>
diff --git a/sc2/src/sc2code/libs/network/socket/socket.h b/sc2/src/sc2code/libs/network/socket/socket.h
index 8b796615e..9a9354440 100644
--- a/sc2/src/sc2code/libs/network/socket/socket.h
+++ b/sc2/src/sc2code/libs/network/socket/socket.h
@@ -24,7 +24,7 @@ typedef struct Socket Socket;
 
 #include "port.h"
 
-#ifdef WIN32
+#ifdef USE_WINSOCK
 #	include "socket_win.h"
 #else
 #	include "socket_bsd.h"