diff --git a/modules/src/system/open.c b/modules/src/system/open.c
index eed31dc13..3ec515a77 100644
--- a/modules/src/system/open.c
+++ b/modules/src/system/open.c
@@ -6,6 +6,7 @@
 
 #include <fcntl.h>
 #include <unistd.h>
+#include <errno.h>
 #include "system.h"
 
 extern File *_get_entry();
@@ -23,11 +24,11 @@ sys_open(path, flag, filep)
 		return 0;
 	switch (flag) {
 	case OP_READ:
-		if ((fd = open(path, 0)) < 0)
+		if ((fd = open(path, O_RDONLY|O_BINARY)) < 0)
 			return 0;
 		break;
 	case OP_APPEND:
-		if ((fd = open(path, 1)) < 0) {
+		if ((fd = open(path, O_WRONLY|O_BINARY)) < 0) {
 			if (access(path, 0) == 0)
 				return 0;
 		}
@@ -40,7 +41,7 @@ sys_open(path, flag, filep)
 		}
 		/* Fall through */
 	case OP_WRITE:
-		if ((fd = creat(path, 0666)) < 0)
+		if ((fd = open(path, O_CREAT|O_WRONLY|O_BINARY, 0666)) < 0)
 			return 0;
 		break;
 	default:
diff --git a/modules/src/system/read.c b/modules/src/system/read.c
index f84c91de9..654ff406d 100644
--- a/modules/src/system/read.c
+++ b/modules/src/system/read.c
@@ -7,12 +7,24 @@
 #include <unistd.h>
 #include "system.h"
 
-int
-sys_read(fp, bufptr, bufsiz, pnbytes)
-	File *fp;
-	char *bufptr;
-	int bufsiz, *pnbytes;
+int sys_read(File* fp, char* bufptr, int bufsiz, int* pnbytes)
 {
-	if (! fp) return 0;
-	return (*pnbytes = read(fp->o_fd, bufptr, bufsiz)) >= 0;
+	if (!fp)
+		return 0;
+	
+	*pnbytes = 0;
+	while (bufsiz != 0)
+	{
+		int len = read(fp->o_fd, bufptr, bufsiz);
+		if (len < 0)
+			return 0;
+		if (len == 0)
+			return *pnbytes != 0;
+
+		*pnbytes += len;
+		bufptr += len;
+		bufsiz -= len;
+	}
+
+	return 1;
 }
diff --git a/modules/src/system/write.c b/modules/src/system/write.c
index 7f87ecc28..af996867c 100644
--- a/modules/src/system/write.c
+++ b/modules/src/system/write.c
@@ -7,12 +7,21 @@
 #include <unistd.h>
 #include "system.h"
 
-int
-sys_write(fp, bufptr, nbytes)
-	File *fp;
-	char *bufptr;
-	int nbytes;
+int sys_write(File* fp, char* bufptr, int nbytes)
 {
-	if (! fp) return 0;
-	return write(fp->o_fd, bufptr, nbytes) == nbytes;
+	if (!fp)
+		return 0;
+	
+	while (nbytes != 0)
+	{
+		int len = write(fp->o_fd, bufptr, nbytes);
+		if (len < 0)
+			return 0;
+
+		bufptr += len;
+		nbytes -= len;
+	}
+
+	return 1;
 }
+
diff --git a/util/ack/files.c b/util/ack/files.c
index e5f00dac3..01a20c992 100644
--- a/util/ack/files.c
+++ b/util/ack/files.c
@@ -54,12 +54,22 @@ int setfiles(trf *phase) {
 	} else {
 		gr_init(&pathname) ;
 		if ( !phase->t_keep && !t_flag ) {
+			/* Unix temporary directory. */
 			char* tmpdir = getenv("TMPDIR");
+			/* Fallback: Windows, running under MSYS2. */
+			if (!tmpdir)
+				tmpdir = getenv("temp");
+			/* Fallback: Windows, running natively. */
+			if (!tmpdir)
+				tmpdir = getenv("TEMP");
+			/* Fallback: Hard-coded directory. */
 			if (!tmpdir)
 				tmpdir = "/tmp";
 			gr_cat(&pathname, tmpdir);
 			gr_cat(&pathname, "/Ack-XXXXXX");
-			mkstemp(pathname.gr_string);
+			int fd = mkstemp(pathname.gr_string);
+			close(fd);
+			remove(pathname.gr_string);
 			out.p_keep=NO ;
 		} else {
 			if ( !p_basename ) {
diff --git a/util/ack/main.c b/util/ack/main.c
index 269e6a571..b466d6025 100644
--- a/util/ack/main.c
+++ b/util/ack/main.c
@@ -56,11 +56,8 @@ int main(int argc, char** argv)
 	}
 	if (callname)
 	{
-		if (machine)
-		{
-			fuerror("can not produce code for both %s and %s", callname, machine);
-		}
-		machine = callname;
+		if (!machine)
+			machine = callname;
 	}
 	if (!machine && !(machine = getenv("ACKM")))
 	{
@@ -329,6 +326,8 @@ static void firstarg(char* argp)
 	register char* name;
 
 	name = strrchr(argp, '/');
+	if (!name)
+		name = strrchr(argp, '\\');
 	if (name && *(name + 1))
 	{
 		name++;
diff --git a/util/ack/rmach.c b/util/ack/rmach.c
index 1a4cd03a1..4d3e2b669 100644
--- a/util/ack/rmach.c
+++ b/util/ack/rmach.c
@@ -141,6 +141,7 @@ static void intrf(void) {
 			new->t_stdin= YES ;
 		} else
 		if ( strcmp(ty_name,STD_OUT)==0 ) {
+			fprintf(stderr, "setting stdout for %s\n", new->t_name);
 			if ( new->t_stdout ) twice=YES ;
 			new->t_stdout= YES ;
 		} else
diff --git a/util/ack/run.c b/util/ack/run.c
index 71eea0592..baafac5e7 100644
--- a/util/ack/run.c
+++ b/util/ack/run.c
@@ -23,7 +23,7 @@ static char rcs_id[] = "$Id$";
 
 #define ARG_MORE 40 /* The size of args chunks to allocate */
 
-static int run_exec(trf*, const char*);
+static int run_exec(trf*);
 static void x_arg(char*);
 
 static char** arglist; /* The first argument */
@@ -81,11 +81,11 @@ int runphase(trf* phase)
 		x_arg(l_content(*elem));
 	}
 	x_arg((char*)0);
-	result = run_exec(phase, prog);
+	result = run_exec(phase);
 	return result;
 }
 
-static int run_exec(trf* phase, const char* prog)
+static int run_exec(trf* phase)
 {
 	int status, child, waitchild;
 	int oldstdin = -1;
@@ -101,7 +101,7 @@ static int run_exec(trf* phase, const char* prog)
 
 		oldstdin = dup(0);
 		close(0);
-		if (open(in.p_path, 0) != 0)
+		if (open(in.p_path, O_RDONLY|O_BINARY) != 0)
 		{
 			error("cannot open %s", in.p_path);
 			exit(1);
@@ -111,13 +111,11 @@ static int run_exec(trf* phase, const char* prog)
 	if (phase->t_stdout)
 	{
 		if (!out.p_path)
-		{
 			fatal("no output file for %s", phase->t_name);
-		}
 
 		oldstdout = dup(1);
 		close(1);
-		if (creat(out.p_path, 0666) != 1)
+		if (open(out.p_path, O_CREAT|O_WRONLY|O_BINARY, 0666) != 1)
 		{
 			close(1);
 			dup(2);
@@ -126,7 +124,7 @@ static int run_exec(trf* phase, const char* prog)
 		}
 	}
 
-	status = sys_system(prog, arglist);
+	status = sys_system(phase->t_prog, (const char* const*) arglist);
 
 	if (oldstdin != -1)
 	{
@@ -137,7 +135,7 @@ static int run_exec(trf* phase, const char* prog)
 
 	if (oldstdout != -1)
 	{
-		close(1);
+		int i = close(1);
 		dup2(oldstdout, 1);
 		close(oldstdout);
 	}
@@ -145,7 +143,7 @@ static int run_exec(trf* phase, const char* prog)
 	if (status)
 	{
 		if (status & 0177)
-			error("%s died with signal %d", prog, status & 0177);
+			error("%s died with signal %d", phase->t_prog, status & 0177);
 
 		/* The assumption is that processes voluntarely
 		   dying with a non-zero status already produced