diff --git a/src/pkg/syscall/mkerrors_windows.sh b/src/pkg/syscall/mkerrors_windows.sh
index f5d4914cff..af95edd001 100755
--- a/src/pkg/syscall/mkerrors_windows.sh
+++ b/src/pkg/syscall/mkerrors_windows.sh
@@ -152,7 +152,7 @@ struct {
 int
 main(void)
 {
-	int i, j, e, iota = 1;
+	int i, e, iota = 1;
 	char buf[1024];
 
 	printf("\n// Go names for Windows errors.\n");
@@ -169,11 +169,6 @@ main(void)
 	printf("\n// Invented values to support what package os and others expects.\n");
 	printf("const (\n");
 	for(i=0; i<nelem(errors); i++) {
-		e = errors[i].value;
-		strcpy(buf, strerror(e));
-		// lowercase first letter: Bad -> bad, but STREAM -> STREAM.
-		if(A <= buf[0] && buf[0] <= Z && a <= buf[1] && buf[1] <= z)
-			buf[0] += a - A;
 		printf("\t%s", errors[i].name);
 		if(iota) {
 			printf(" = APPLICATION_ERROR + iota");
@@ -189,9 +184,6 @@ main(void)
 	printf("var errors = [...]string {\n");
 	for(i=0; i<nelem(errors); i++) {
 		e = errors[i].value;
-		for(j=0; j<i; j++)
-			if(errors[j].value == e)	// duplicate value
-				goto next;
 		strcpy(buf, strerror(e));
 		// lowercase first letter: Bad -> bad, but STREAM -> STREAM.
 		if(A <= buf[0] && buf[0] <= Z && a <= buf[1] && buf[1] <= z)
diff --git a/src/pkg/syscall/zerrors_windows_386.go b/src/pkg/syscall/zerrors_windows_386.go
index a6bed6ea6b..ae4506fac0 100644
--- a/src/pkg/syscall/zerrors_windows_386.go
+++ b/src/pkg/syscall/zerrors_windows_386.go
@@ -174,6 +174,7 @@ var errors = [...]string{
 	ECONNREFUSED - APPLICATION_ERROR:    "connection refused",
 	ECONNRESET - APPLICATION_ERROR:      "connection reset by peer",
 	EDEADLK - APPLICATION_ERROR:         "resource deadlock avoided",
+	EDEADLOCK - APPLICATION_ERROR:       "resource deadlock avoided",
 	EDESTADDRREQ - APPLICATION_ERROR:    "destination address required",
 	EDOM - APPLICATION_ERROR:            "numerical argument out of domain",
 	EDOTDOT - APPLICATION_ERROR:         "RFS specific error",
@@ -246,6 +247,7 @@ var errors = [...]string{
 	ENOTTY - APPLICATION_ERROR:          "inappropriate ioctl for device",
 	ENOTUNIQ - APPLICATION_ERROR:        "name not unique on network",
 	ENXIO - APPLICATION_ERROR:           "no such device or address",
+	EOPNOTSUPP - APPLICATION_ERROR:      "operation not supported",
 	EOVERFLOW - APPLICATION_ERROR:       "value too large for defined data type",
 	EOWNERDEAD - APPLICATION_ERROR:      "owner died",
 	EPERM - APPLICATION_ERROR:           "operation not permitted",
@@ -274,6 +276,7 @@ var errors = [...]string{
 	EUCLEAN - APPLICATION_ERROR:         "structure needs cleaning",
 	EUNATCH - APPLICATION_ERROR:         "protocol driver not attached",
 	EUSERS - APPLICATION_ERROR:          "too many users",
+	EWOULDBLOCK - APPLICATION_ERROR:     "resource temporarily unavailable",
 	EXDEV - APPLICATION_ERROR:           "invalid cross-device link",
 	EXFULL - APPLICATION_ERROR:          "exchange full",
 	EWINDOWS - APPLICATION_ERROR:        "not supported by windows",