diff --git a/src/gdb_hostio.c b/src/gdb_hostio.c
index 20fb8f4b..82ff0a6d 100644
--- a/src/gdb_hostio.c
+++ b/src/gdb_hostio.c
@@ -29,25 +29,26 @@ int gdb_main_loop(struct target_controller *, bool in_syscall);
 int hostio_reply(struct target_controller *tc, char *pbuf, int len)
 {
 	(void)len;
-	int retcode, items;
+	int retcode, items, errno_;
 	char c, *p;
 	if (pbuf[1] == '-')
 		p = &pbuf[2];
 	else
 		p = &pbuf[1];
-	items = sscanf(p, "%x,%x,%c", &retcode, &tc->errno_, &c);
+	items = sscanf(p, "%x,%x,%c", &retcode, &errno_, &c);
 	if (pbuf[1] == '-')
 		retcode = -retcode;
 
 	/* if break is requested */
 	tc->interrupted = items == 3 && c == 'C';
+	tc->errno_ = errno_;
 
 	return retcode;
 }
 
 /* Interface to host system calls */
 int hostio_open(struct target_controller *tc,
-	        target_addr path, unsigned path_len,
+	        target_addr path, size_t path_len,
                 enum target_open_flags flags, mode_t mode)
 {
 	gdb_putpacket_f("Fopen,%08X/%X,%08X,%08X", path, path_len, flags, mode);;;;
@@ -82,8 +83,8 @@ long hostio_lseek(struct target_controller *tc,
 }
 
 int hostio_rename(struct target_controller *tc,
-	           target_addr oldpath, unsigned old_len,
-	           target_addr newpath, unsigned new_len)
+	           target_addr oldpath, size_t old_len,
+	           target_addr newpath, size_t new_len)
 {
 	gdb_putpacket_f("Frename,%08X/%X,%08X/%X",
 	                oldpath, old_len, newpath, new_len);
@@ -91,14 +92,14 @@ int hostio_rename(struct target_controller *tc,
 }
 
 int hostio_unlink(struct target_controller *tc,
-	           target_addr path, unsigned path_len)
+	           target_addr path, size_t path_len)
 {
 	gdb_putpacket_f("Funlink,%08X/%X", path, path_len);
 	return gdb_main_loop(tc, true);
 }
 
 int hostio_stat(struct target_controller *tc,
-	         target_addr path, unsigned path_len, target_addr buf)
+	         target_addr path, size_t path_len, target_addr buf)
 {
 	gdb_putpacket_f("Fstat,%08X/%X,%08X", path, path_len, buf);
 	return gdb_main_loop(tc, true);
@@ -124,7 +125,7 @@ int hostio_isatty(struct target_controller *tc, int fd)
 }
 
 int hostio_system(struct target_controller *tc,
-	           target_addr cmd, unsigned cmd_len)
+	          target_addr cmd, size_t cmd_len)
 {
 	gdb_putpacket_f("Fsystem,%08X/%X", cmd, cmd_len);
 	return gdb_main_loop(tc, true);
diff --git a/src/gdb_hostio.h b/src/gdb_hostio.h
index eaa97bd7..f95f707f 100644
--- a/src/gdb_hostio.h
+++ b/src/gdb_hostio.h
@@ -26,7 +26,7 @@ int hostio_reply(struct target_controller *tc, char *packet, int len);
 
 /* Interface to host system calls */
 int hostio_open(struct target_controller *,
-	        target_addr path, unsigned path_len,
+	        target_addr path, size_t path_len,
                 enum target_open_flags flags, mode_t mode);
 int hostio_close(struct target_controller *, int fd);
 int hostio_read(struct target_controller *,
@@ -36,18 +36,18 @@ int hostio_write(struct target_controller *,
 long hostio_lseek(struct target_controller *,
 	           int fd, long offset, enum target_seek_flag flag);
 int hostio_rename(struct target_controller *,
-	           target_addr oldpath, unsigned old_len,
-	           target_addr newpath, unsigned new_len);
+	           target_addr oldpath, size_t old_len,
+	           target_addr newpath, size_t new_len);
 int hostio_unlink(struct target_controller *,
-	           target_addr path, unsigned path_len);
+	           target_addr path, size_t path_len);
 int hostio_stat(struct target_controller *,
-	         target_addr path, unsigned path_len, target_addr buf);
+	         target_addr path, size_t path_len, target_addr buf);
 int hostio_fstat(struct target_controller *, int fd, target_addr buf);
 int hostio_gettimeofday(struct target_controller *,
 		         target_addr tv, target_addr tz);
 int hostio_isatty(struct target_controller *, int fd);
 int hostio_system(struct target_controller *,
-	           target_addr cmd, unsigned cmd_len);
+	           target_addr cmd, size_t cmd_len);
 
 #endif
 
diff --git a/src/include/target.h b/src/include/target.h
index 8ca7e74c..86c7d986 100644
--- a/src/include/target.h
+++ b/src/include/target.h
@@ -79,7 +79,7 @@ struct target_controller {
 
 	/* Interface to host system calls */
 	int (*open)(struct target_controller *,
-	            target_addr path, unsigned path_len,
+	            target_addr path, size_t path_len,
 	            enum target_open_flags flags, mode_t mode);
 	int (*close)(struct target_controller *, int fd);
 	int (*read)(struct target_controller *,
@@ -89,18 +89,18 @@ struct target_controller {
 	long (*lseek)(struct target_controller *,
 	              int fd, long offset, enum target_seek_flag flag);
 	int (*rename)(struct target_controller *,
-	              target_addr oldpath, unsigned old_len,
-	              target_addr newpath, unsigned new_len);
+	              target_addr oldpath, size_t old_len,
+	              target_addr newpath, size_t new_len);
 	int (*unlink)(struct target_controller *,
-	              target_addr path, unsigned path_len);
+	              target_addr path, size_t path_len);
 	int (*stat)(struct target_controller *,
-	            target_addr path, unsigned path_len, target_addr buf);
+	            target_addr path, size_t path_len, target_addr buf);
 	int (*fstat)(struct target_controller *, int fd, target_addr buf);
 	int (*gettimeofday)(struct target_controller *,
 	                    target_addr tv, target_addr tz);
 	int (*isatty)(struct target_controller *, int fd);
 	int (*system)(struct target_controller *,
-	              target_addr cmd, unsigned cmd_len);
+	              target_addr cmd, size_t cmd_len);
 	enum target_errno errno_;
 	bool interrupted;
 };
diff --git a/src/target/target.c b/src/target/target.c
index 70224a13..750b17a6 100644
--- a/src/target/target.c
+++ b/src/target/target.c
@@ -424,7 +424,7 @@ void tc_printf(target *t, const char *fmt, ...)
 }
 
 /* Interface to host system calls */
-int tc_open(target *t, target_addr path, unsigned plen,
+int tc_open(target *t, target_addr path, size_t plen,
             enum target_open_flags flags, mode_t mode)
 {
 	if (t->tc->open == NULL) {
@@ -464,8 +464,8 @@ long tc_lseek(target *t, int fd, long offset, enum target_seek_flag flag)
 	return t->tc->lseek(t->tc, fd, offset, flag);
 }
 
-int tc_rename(target *t, target_addr oldpath, unsigned oldlen,
-                         target_addr newpath, unsigned newlen)
+int tc_rename(target *t, target_addr oldpath, size_t oldlen,
+                         target_addr newpath, size_t newlen)
 {
 	if (t->tc->rename == NULL) {
 		t->tc->errno_ = TARGET_ENOENT;
@@ -474,7 +474,7 @@ int tc_rename(target *t, target_addr oldpath, unsigned oldlen,
 	return t->tc->rename(t->tc, oldpath, oldlen, newpath, newlen);
 }
 
-int tc_unlink(target *t, target_addr path, unsigned plen)
+int tc_unlink(target *t, target_addr path, size_t plen)
 {
 	if (t->tc->unlink == NULL) {
 		t->tc->errno_ = TARGET_ENOENT;
@@ -483,7 +483,7 @@ int tc_unlink(target *t, target_addr path, unsigned plen)
 	return t->tc->unlink(t->tc, path, plen);
 }
 
-int tc_stat(target *t, target_addr path, unsigned plen, target_addr buf)
+int tc_stat(target *t, target_addr path, size_t plen, target_addr buf)
 {
 	if (t->tc->stat == NULL) {
 		t->tc->errno_ = TARGET_ENOENT;
@@ -516,7 +516,7 @@ int tc_isatty(target *t, int fd)
 	return t->tc->isatty(t->tc, fd);
 }
 
-int tc_system(target *t, target_addr cmd, unsigned cmdlen)
+int tc_system(target *t, target_addr cmd, size_t cmdlen)
 {
 	if (t->tc->system == NULL) {
 		return -1;
diff --git a/src/target/target_internal.h b/src/target/target_internal.h
index 6042a46c..9f55ea58 100644
--- a/src/target/target_internal.h
+++ b/src/target/target_internal.h
@@ -142,21 +142,21 @@ void target_mem_write8(target *t, uint32_t addr, uint8_t value);
 void tc_printf(target *t, const char *fmt, ...);
 
 /* Interface to host system calls */
-int tc_open(target *, target_addr path, unsigned plen,
+int tc_open(target *, target_addr path, size_t plen,
             enum target_open_flags flags, mode_t mode);
 int tc_close(target *t, int fd);
 int tc_read(target *t, int fd, target_addr buf, unsigned int count);
 int tc_write(target *t, int fd, target_addr buf, unsigned int count);
 long tc_lseek(target *t, int fd, long offset,
               enum target_seek_flag flag);
-int tc_rename(target *t, target_addr oldpath, unsigned oldlen,
-                         target_addr newpath, unsigned newlen);
-int tc_unlink(target *t, target_addr path, unsigned plen);
-int tc_stat(target *t, target_addr path, unsigned plen, target_addr buf);
+int tc_rename(target *t, target_addr oldpath, size_t oldlen,
+                         target_addr newpath, size_t newlen);
+int tc_unlink(target *t, target_addr path, size_t plen);
+int tc_stat(target *t, target_addr path, size_t plen, target_addr buf);
 int tc_fstat(target *t, int fd, target_addr buf);
 int tc_gettimeofday(target *t, target_addr tv, target_addr tz);
 int tc_isatty(target *t, int fd);
-int tc_system(target *t, target_addr cmd, unsigned cmdlen);
+int tc_system(target *t, target_addr cmd, size_t cmdlen);
 
 /* Probe for various targets.
  * Actual functions implemented in their respective drivers.