diff --git a/src/lib/w32/posixfile.c b/src/lib/w32/posixfile.c
index 5b21d696..5bebc76d 100644
--- a/src/lib/w32/posixfile.c
+++ b/src/lib/w32/posixfile.c
@@ -37,7 +37,7 @@
 #include "unistd.h"
 
 int
-posix_mkdir(const char *dirname, int perm)
+posix_mkdir(const char *dirname, mode_t perm)
 {
     int result;
 
diff --git a/src/lib/w32/posixio.c b/src/lib/w32/posixio.c
index b1e706a7..80573c7c 100644
--- a/src/lib/w32/posixio.c
+++ b/src/lib/w32/posixio.c
@@ -249,7 +249,7 @@ posix_accept(int fd, struct sockaddr *addr, socklen_t *addrlen)
  */
 #undef bind
 int
-posix_bind(int fd, const struct sockaddr *name, int namelen)
+posix_bind(int fd, const struct sockaddr *name, socklen_t namelen)
 {
     SOCKET_FUNCTION(bind(handle, name, namelen))
 }
@@ -270,7 +270,7 @@ posix_listen(int fd, int backlog)
 #undef setsockopt
 int
 posix_setsockopt(int fd, int level, int optname,
-		      const void *optval, int optlen)
+		      const void *optval, socklen_t optlen)
 {
     /*
      * SO_REUSEADDR requests from tcp_listen.c
@@ -388,8 +388,8 @@ posix_fstat(int fd, struct stat *buffer)
 /*
  * POSIX equivalent for lseek().
  */
-int
-posix_lseek(int fd, long offset, int origin)
+off_t
+posix_lseek(int fd, off_t offset, int origin)
 {
     FILE_FUNCTION(FDMAP_IO_FILE, _lseek(handle, offset, origin))
 }
@@ -454,8 +454,8 @@ posix_open(const char *fname, int oflag, ...)
 /*
  * POSIX equivalent for read().
  */
-int
-posix_read(int fd, void *buffer, unsigned int count)
+ssize_t
+posix_read(int fd, void *buffer, size_t count)
 {
     SHARED_FUNCTION(recv(handle, buffer, count, 0),
 	_read(handle, buffer, count))
@@ -509,8 +509,8 @@ readv(int fd, const struct iovec *iov, int iovcnt)
 /*
  * POSIX equivalent for write().
  */
-int
-posix_write(int fd, const void *buffer, unsigned int count)
+ssize_t
+posix_write(int fd, const void *buffer, size_t count)
 {
     SHARED_FUNCTION(send(handle, buffer, count, 0),
 	_write(handle, buffer, count))
diff --git a/src/lib/w32/unistd.h b/src/lib/w32/unistd.h
index cb446454..cf24bf8e 100644
--- a/src/lib/w32/unistd.h
+++ b/src/lib/w32/unistd.h
@@ -40,6 +40,7 @@
 #include <direct.h>
 #include "sys/socket.h"
 #include <sys/stat.h>
+#include "w32misc.h"
 
 /*
  * getopt.c
@@ -53,7 +54,7 @@ extern int optind, opterr, optopt;
  */
 #define mkdir(dir, perm)    posix_mkdir((dir), (perm))
 
-extern int posix_mkdir(const char *dirname, int perm);
+extern int posix_mkdir(const char *dirname, mode_t perm);
 
 /*
  * posixio.c
@@ -130,19 +131,19 @@ struct flock
 extern int posix_fd2socket(int fd);
 
 extern int posix_accept(int fd, struct sockaddr *addr, socklen_t *addrlen);
-extern int posix_bind(int fd, const struct sockaddr *name, int namelen);
+extern int posix_bind(int fd, const struct sockaddr *name, socklen_t namelen);
 extern int posix_listen(int fd, int backlog);
 extern int posix_setsockopt(int fd, int level, int optname,
-		      const void *optval, int optlen);
+		      const void *optval, socklen_t optlen);
 extern int posix_shutdown(int fd, int how);
 extern int posix_socket(int domain, int type, int protocol);
 
 extern int posix_close(int fd);
 extern int posix_fstat(int fd, struct stat *buffer);
-extern int posix_lseek(int fd, long offset, int origin);
+extern off_t posix_lseek(int fd, off_t offset, int origin);
 extern int posix_open(const char *fname, int oflag, ...);
-extern int posix_read(int fd, void *buffer, unsigned int count);
-extern int posix_write(int fd, const void *buffer, unsigned int count);
+extern ssize_t posix_read(int fd, void *buffer, size_t count);
+extern ssize_t posix_write(int fd, const void *buffer, size_t count);
 
 extern int posix_fileno(FILE *stream);
 extern int posix_fsync(int fd);
diff --git a/src/lib/w32/w32misc.h b/src/lib/w32/w32misc.h
index 3df65eb1..d54d1738 100644
--- a/src/lib/w32/w32misc.h
+++ b/src/lib/w32/w32misc.h
@@ -52,8 +52,10 @@
 #define srandom srand
 
 /* sys/types.h */
-typedef long ssize_t;
+typedef int mode_t;
+typedef long off_t;
 typedef int pid_t;
+typedef long ssize_t;
 
 /* time.h */
 struct tm;