diff --git a/src/cmd/cc/lex.c b/src/cmd/cc/lex.c
index c9facc667e9..fd74edb9d28 100644
--- a/src/cmd/cc/lex.c
+++ b/src/cmd/cc/lex.c
@@ -38,7 +38,7 @@
 int
 systemtype(int sys)
 {
-#ifdef __MINGW32__
+#ifdef _WIN32
 	return sys&Windows;
 #else
 	return sys&Plan9;
diff --git a/src/cmd/godefs/main.c b/src/cmd/godefs/main.c
index 6ff542f4897..d31d298a5e1 100644
--- a/src/cmd/godefs/main.c
+++ b/src/cmd/godefs/main.c
@@ -82,7 +82,7 @@
 
 #include "a.h"
 
-#ifdef __MINGW32__
+#ifdef _WIN32
 int
 spawn(char *prog, char **argv)
 {
diff --git a/src/lib9/dirfwstat.c b/src/lib9/dirfwstat.c
index 15f1c125205..fe9153b9b7e 100644
--- a/src/lib9/dirfwstat.c
+++ b/src/lib9/dirfwstat.c
@@ -61,7 +61,7 @@ dirfwstat(int fd, Dir *dir)
 	struct timeval tv[2];
 
 	ret = 0;
-#ifndef __MINGW32__
+#ifndef _WIN32
 	if(~dir->mode != 0){
 		if(fchmod(fd, dir->mode) < 0)
 			ret = -1;
diff --git a/src/lib9/dirstat.c b/src/lib9/dirstat.c
index 6c476753b0a..6d804ca7c7f 100644
--- a/src/lib9/dirstat.c
+++ b/src/lib9/dirstat.c
@@ -39,7 +39,7 @@ dirstat(char *file)
 	Dir *d;
 	char *str;
 
-#ifdef __MINGW32__
+#ifdef _WIN32
 	if(stat(file, &st) < 0)
 		return nil;
 	lst = st;
diff --git a/src/lib9/time.c b/src/lib9/time.c
index 720dd702eb2..7394e9e6037 100644
--- a/src/lib9/time.c
+++ b/src/lib9/time.c
@@ -25,7 +25,7 @@ THE SOFTWARE.
 #include <u.h>
 #include <sys/time.h>
 #include <time.h>
-#ifndef __MINGW32__
+#ifndef _WIN32
 #include <sys/resource.h>
 #endif
 #define NOPLAN9DEFINES
@@ -34,7 +34,7 @@ THE SOFTWARE.
 long
 p9times(long *t)
 {
-#ifdef __MINGW32__
+#ifdef _WIN32
 	memset(t, 0, 4*sizeof(long));
 #else
 	struct rusage ru, cru;
diff --git a/src/libbio/bseek.c b/src/libbio/bseek.c
index be00ab1a7df..29149810895 100644
--- a/src/libbio/bseek.c
+++ b/src/libbio/bseek.c
@@ -33,7 +33,7 @@ Bseek(Biobuf *bp, vlong offset, int base)
 	vlong n, d;
 	int bufsz;
 
-#ifndef __MINGW32__
+#ifndef _WIN32
 	if(sizeof(offset) != sizeof(off_t)) {
 		fprint(2, "Bseek: libbio compiled with %d-byte offset\n", sizeof(off_t));
 		abort();
diff --git a/src/libcgo/386.S b/src/libcgo/386.S
index cca79cdd516..02cbe345347 100755
--- a/src/libcgo/386.S
+++ b/src/libcgo/386.S
@@ -5,7 +5,7 @@
 /*
  * Apple still insists on underscore prefixes for C function names.
  */
-#if defined(__APPLE__) || defined(__MINGW32__)
+#if defined(__APPLE__) || defined(_WIN32)
 #define EXT(s) _##s
 #else
 #define EXT(s) s
diff --git a/src/libcgo/amd64.S b/src/libcgo/amd64.S
index 178c33cde06..083c2bc9417 100644
--- a/src/libcgo/amd64.S
+++ b/src/libcgo/amd64.S
@@ -5,7 +5,7 @@
 /*
  * Apple still insists on underscore prefixes for C function names.
  */
-#if defined(__APPLE__) || defined(__MINGW64__)
+#if defined(__APPLE__) || defined(_WIN32)
 #define EXT(s) _##s
 #else
 #define EXT(s) s