diff --git a/moo/lib/comp.c b/moo/lib/comp.c
index 9a9dc39..511dfac 100644
--- a/moo/lib/comp.c
+++ b/moo/lib/comp.c
@@ -7740,9 +7740,8 @@ static int process_class_module_import (moo_t* moo)
 		return -1;
 	}
 
-	if (TOKEN_NAME_LEN(moo) <= 0 || 
-		TOKEN_NAME_LEN(moo) > MOO_MOD_NAME_LEN_MAX ||
-		moo_find_oochar(TOKEN_NAME_PTR(moo), TOKEN_NAME_LEN(moo), '-') )
+	if (TOKEN_NAME_LEN(moo) <= 0 || TOKEN_NAME_LEN(moo) > MOO_MOD_NAME_LEN_MAX ||
+	    moo_find_oochar(TOKEN_NAME_PTR(moo), TOKEN_NAME_LEN(moo), '-') )
 	{
 		/* check for a bad module name. 
 		 * also disallow a dash in the name - i like converting
diff --git a/moo/lib/err.c b/moo/lib/err.c
index 267e2fa..7bcc014 100644
--- a/moo/lib/err.c
+++ b/moo/lib/err.c
@@ -226,153 +226,6 @@ static const moo_ooch_t* synerr_to_errstr (moo_synerrnum_t errnum)
 #	include <errno.h>
 #endif
 
-moo_errnum_t moo_syserr_to_errnum (int e)
-{
-#if 0
-	/* -------------------------------------- */
-	/* currently 'e' is expected to be 'errno'. it doesn't support GetLastError() on win32 or APIRET on os2 yet */
-	/* -------------------------------------- */
-#if defined(__OS2__)
-	/* APIRET e */
-	switch (e)
-	{
-		case ERROR_NOT_ENOUGH_MEMORY: return MOO_ESYSMEM;
-
-		case ERROR_INVALID_PARAMETER: 
-		case ERROR_INVALID_HANDLE: 
-		case ERROR_INVALID_NAME: return MOO_EINVAL;
-
-		case ERROR_ACCESS_DENIED: 
-		case ERROR_SHARING_VIOLATION: return MOO_EACCES;
-
-		case ERROR_FILE_NOT_FOUND:
-		case ERROR_PATH_NOT_FOUND: return MOO_ENOENT;
-
-		case ERROR_ALREADY_EXISTS: return MOO_EEXIST;
-
-		/*TODO: add more mappings */
-		default: return MOO_ESYSERR;
-	}
-#elif defined(macintosh)
-	switch (e)
-	{
-		case notEnoughMemoryErr: return MOO_ESYSMEM;
-		case paramErr: return MOO_EINVAL;
-
-		case qErr: /* queue element not found during deletion */
-		case fnfErr: /* file not found */
-		case dirNFErr: /* direcotry not found */
-		case resNotFound: /* resource not found */
-		case resFNotFound: /* resource file not found */
-		case nbpNotFound: /* name not found on remove */
-			return MOO_ENOENT;
-
-		/*TODO: add more mappings */
-		default: return MOO_ESYSERR;
-	}
-
-#else
-
-	switch (e)
-	{
-		case ENOMEM: return MOO_ESYSMEM;
-		case EINVAL: return MOO_EINVAL;
-
-	#if defined(EBUSY)
-		case EBUSY: return MOO_EBUSY;
-	#endif
-		case EACCES: return MOO_EACCES;
-	#if defined(EPERM)
-		case EPERM: return MOO_EPERM;
-	#endif
-	#if defined(ENOTDIR)
-		case ENOTDIR: return MOO_ENOTDIR;
-	#endif
-		case ENOENT: return MOO_ENOENT;
-	#if defined(EEXIST)
-		case EEXIST: return MOO_EEXIST;
-	#endif
-	#if defined(EINTR)
-		case EINTR:  return MOO_EINTR;
-	#endif
-
-	#if defined(EPIPE)
-		case EPIPE:  return MOO_EPIPE;
-	#endif
-
-	#if defined(EAGAIN) && defined(EWOULDBLOCK) && (EAGAIN != EWOULDBLOCK)
-		case EAGAIN: 
-		case EWOULDBLOCK: return MOO_EAGAIN;
-	#elif defined(EAGAIN)
-		case EAGAIN: return MOO_EAGAIN;
-	#elif defined(EWOULDBLOCK)
-		case EWOULDBLOCK: return MOO_EAGAIN;
-	#endif
-
-	#if defined(EBADF)
-		case EBADF: return MOO_EBADHND;
-	#endif
-
-	#if defined(EIO)
-		case EIO: return MOO_EIOERR;
-	#endif
-
-		default: return MOO_ESYSERR;
-	}
-#endif
-
-#else
-	/* ------------------------------------------------------------------- */
-	switch (e)
-	{
-		case ENOMEM: return MOO_ESYSMEM;
-		case EINVAL: return MOO_EINVAL;
-
-	#if defined(EBUSY)
-		case EBUSY: return MOO_EBUSY;
-	#endif
-		case EACCES: return MOO_EACCES;
-	#if defined(EPERM)
-		case EPERM: return MOO_EPERM;
-	#endif
-	#if defined(ENOTDIR)
-		case ENOTDIR: return MOO_ENOTDIR;
-	#endif
-		case ENOENT: return MOO_ENOENT;
-	#if defined(EEXIST)
-		case EEXIST: return MOO_EEXIST;
-	#endif
-	#if defined(EINTR)
-		case EINTR:  return MOO_EINTR;
-	#endif
-
-	#if defined(EPIPE)
-		case EPIPE:  return MOO_EPIPE;
-	#endif
-
-	#if defined(EAGAIN) && defined(EWOULDBLOCK) && (EAGAIN != EWOULDBLOCK)
-		case EAGAIN: 
-		case EWOULDBLOCK: return MOO_EAGAIN;
-	#elif defined(EAGAIN)
-		case EAGAIN: return MOO_EAGAIN;
-	#elif defined(EWOULDBLOCK)
-		case EWOULDBLOCK: return MOO_EAGAIN;
-	#endif
-
-	#if defined(EBADF)
-		case EBADF: return MOO_EBADHND;
-	#endif
-
-	#if defined(EIO)
-		case EIO: return MOO_EIOERR;
-	#endif
-
-		default: return MOO_ESYSERR;
-	}
-	/* ------------------------------------------------------------------- */
-#endif
-}
-
 /* -------------------------------------------------------------------------- 
  * ERROR NUMBER/MESSAGE HANDLING
  * -------------------------------------------------------------------------- */
@@ -401,20 +254,22 @@ void moo_seterrnum (moo_t* moo, moo_errnum_t errnum)
 	moo->errmsg.len = 0; 
 }
 
-void moo_seterrwithsyserr (moo_t* moo, int syserr)
+void moo_seterrwithsyserr (moo_t* moo, int syserr_type, int syserr_code)
 {
+	moo_errnum_t errnum;
+
 	if (moo->shuterr) return;
 
 	if (moo->vmprim.syserrstrb)
 	{
-		moo->vmprim.syserrstrb (moo, syserr, moo->errmsg.tmpbuf.bch, MOO_COUNTOF(moo->errmsg.tmpbuf.bch));
-		moo_seterrbfmt (moo, moo_syserr_to_errnum(syserr), "%hs", moo->errmsg.tmpbuf.bch);
+		errnum = moo->vmprim.syserrstrb (moo, syserr_type, syserr_code, moo->errmsg.tmpbuf.bch, MOO_COUNTOF(moo->errmsg.tmpbuf.bch));
+		moo_seterrbfmt (moo, errnum, "%hs", moo->errmsg.tmpbuf.bch);
 	}
 	else
 	{
 		MOO_ASSERT (moo, moo->vmprim.syserrstru != MOO_NULL);
-		moo->vmprim.syserrstru (moo, syserr, moo->errmsg.tmpbuf.uch, MOO_COUNTOF(moo->errmsg.tmpbuf.uch));
-		moo_seterrbfmt (moo, moo_syserr_to_errnum(syserr), "%ls", moo->errmsg.tmpbuf.uch);
+		errnum = moo->vmprim.syserrstru (moo, syserr_type, syserr_code, moo->errmsg.tmpbuf.uch, MOO_COUNTOF(moo->errmsg.tmpbuf.uch));
+		moo_seterrbfmt (moo, errnum, "%ls", moo->errmsg.tmpbuf.uch);
 	}
 }
 
diff --git a/moo/lib/main.c b/moo/lib/main.c
index db0736f..c40af2d 100644
--- a/moo/lib/main.c
+++ b/moo/lib/main.c
@@ -827,16 +827,162 @@ static void log_write (moo_t* moo, moo_bitmask_t mask, const moo_ooch_t* msg, mo
 	flush_log (moo, logfd);
 }
 
-static void syserrstrb (moo_t* moo, int syserr, moo_bch_t* buf, moo_oow_t len)
+static moo_errnum_t errno_to_errnum (int errcode)
 {
-#if defined(HAVE_STRERROR_R)
-	strerror_r (syserr, buf, len);
-#else
-	/* this is not thread safe */
-	moo_copy_bcstr (buf, len, strerror(syserr));
-#endif
+	switch (errcode)
+	{
+		case ENOMEM: return MOO_ESYSMEM;
+		case EINVAL: return MOO_EINVAL;
+
+	#if defined(EBUSY)
+		case EBUSY: return MOO_EBUSY;
+	#endif
+		case EACCES: return MOO_EACCES;
+	#if defined(EPERM)
+		case EPERM: return MOO_EPERM;
+	#endif
+	#if defined(ENOTDIR)
+		case ENOTDIR: return MOO_ENOTDIR;
+	#endif
+		case ENOENT: return MOO_ENOENT;
+	#if defined(EEXIST)
+		case EEXIST: return MOO_EEXIST;
+	#endif
+	#if defined(EINTR)
+		case EINTR:  return MOO_EINTR;
+	#endif
+
+	#if defined(EPIPE)
+		case EPIPE:  return MOO_EPIPE;
+	#endif
+
+	#if defined(EAGAIN) && defined(EWOULDBLOCK) && (EAGAIN != EWOULDBLOCK)
+		case EAGAIN: 
+		case EWOULDBLOCK: return MOO_EAGAIN;
+	#elif defined(EAGAIN)
+		case EAGAIN: return MOO_EAGAIN;
+	#elif defined(EWOULDBLOCK)
+		case EWOULDBLOCK: return MOO_EAGAIN;
+	#endif
+
+	#if defined(EBADF)
+		case EBADF: return MOO_EBADHND;
+	#endif
+
+	#if defined(EIO)
+		case EIO: return MOO_EIOERR;
+	#endif
+
+		default: return MOO_ESYSERR;
+	}
 }
 
+#if defined(_WIN32)
+static moo_errnum_t winerr_to_errnum (DWORD errcode)
+{
+	return MOO_ESYSERR;
+}
+#endif
+
+#if defined(__OS2__)
+static moo_errnum_t os2err_to_errnum (APIRET errcode)
+{
+	/* APIRET e */
+	switch (errcode)
+	{
+		case ERROR_NOT_ENOUGH_MEMORY:
+			return MOO_ESYSMEM;
+
+		case ERROR_INVALID_PARAMETER: 
+		case ERROR_INVALID_HANDLE: 
+		case ERROR_INVALID_NAME:
+			return MOO_EINVAL;
+
+		case ERROR_ACCESS_DENIED: 
+		case ERROR_SHARING_VIOLATION:
+			return MOO_EACCES;
+
+		case ERROR_FILE_NOT_FOUND:
+		case ERROR_PATH_NOT_FOUND:
+			return MOO_ENOENT;
+
+		case ERROR_ALREADY_EXISTS:
+			return MOO_EEXIST;
+
+		/*TODO: add more mappings */
+		default:
+			return MOO_ESYSERR;
+	}
+}
+#endif
+
+#if defined(macintosh)
+static moo_errnum_t macerr_to_errnum (int errcode)
+{
+	switch (e)
+	{
+		case notEnoughMemoryErr:
+			return MOO_ESYSMEM;
+		case paramErr:
+			return MOO_EINVAL;
+
+		case qErr: /* queue element not found during deletion */
+		case fnfErr: /* file not found */
+		case dirNFErr: /* direcotry not found */
+		case resNotFound: /* resource not found */
+		case resFNotFound: /* resource file not found */
+		case nbpNotFound: /* name not found on remove */
+			return MOO_ENOENT;
+
+		/*TODO: add more mappings */
+		default: 
+			return MOO_ESYSERR;
+	}
+}
+#endif
+
+static moo_errnum_t syserrstrb (moo_t* moo, int syserr_type, int syserr_code, moo_bch_t* buf, moo_oow_t len)
+{
+	switch (syserr_type)
+	{
+		case 1: 
+		#if defined(_WIN32)
+			DWORD rc;
+			rc = FormatMessageA (
+				FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+				NULL, syserr_code, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), 
+				buf, len, MOO_NULL
+			);
+			while (rc > 0 && buf[rc - 1] == '\r' || buf[rc - 1] == '\n') buf[--rc] = '\0';
+			return winerr_to_errnum(syserr_code);
+		#elif defined(__OS2__)
+			/* TODO: convert code to string */
+			moo_copy_bcstr (buf, len, "system error");
+			return os2err_to_errnum(syserr_code);
+		#elif defined(macintosh)
+			/* TODO: convert code to string */
+			moo_copy_bcstr (buf, len, "system error");
+			return os2err_to_errnum(syserr_code);
+		#else
+			/* in other systems, errno is still the native system error code.
+			 * fall thru */
+		#endif
+
+		case 0:
+		#if defined(HAVE_STRERROR_R)
+			strerror_r (syserr_code, buf, len);
+		#else
+			/* this is not thread safe */
+			moo_copy_bcstr (buf, len, strerror(syserr_code));
+		#endif
+			return errno_to_errnum(syserr_code);
+	}
+
+	moo_copy_bcstr (buf, len, "system error");
+	return MOO_ESYSERR;
+}
+
+
 /* ========================================================================= */
 
 #if defined(USE_WIN_DLL)
@@ -1177,7 +1323,7 @@ static int _add_poll_fd (moo_t* moo, int fd, int event_mask)
 	ev.revents = 0;
 	if (write(xtn->ep, &ev, MOO_SIZEOF(ev)) != MOO_SIZEOF(ev))
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		MOO_DEBUG2 (moo, "Cannot add file descriptor %d to devpoll - %hs\n", fd, strerror(errno));
 		return -1;
 	}
@@ -1201,7 +1347,7 @@ static int _add_poll_fd (moo_t* moo, int fd, int event_mask)
 	ev.data.fd = fd;
 	if (epoll_ctl(xtn->ep, EPOLL_CTL_ADD, fd, &ev) == -1)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		MOO_DEBUG2 (moo, "Cannot add file descriptor %d to epoll - %hs\n", fd, strerror(errno));
 		return -1;
 	}
@@ -1281,7 +1427,7 @@ static int _del_poll_fd (moo_t* moo, int fd)
 	ev.revents = 0;
 	if (write (xtn->ep, &ev, MOO_SIZEOF(ev)) != MOO_SIZEOF(ev))
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		MOO_DEBUG2 (moo, "Cannot remove file descriptor %d from devpoll - %hs\n", fd, strerror(errno));
 		return -1;
 	}
@@ -1296,7 +1442,7 @@ static int _del_poll_fd (moo_t* moo, int fd)
 	memset (&ev, 0, MOO_SIZEOF(ev));
 	if (epoll_ctl (xtn->ep, EPOLL_CTL_DEL, fd, &ev) == -1)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		MOO_DEBUG2 (moo, "Cannot remove file descriptor %d from epoll - %hs\n", fd, strerror(errno));
 		return -1;
 	}
@@ -1384,7 +1530,7 @@ static int _mod_poll_fd (moo_t* moo, int fd, int event_mask)
 	ev.data.fd = fd;
 	if (epoll_ctl(xtn->ep, EPOLL_CTL_MOD, fd, &ev) == -1)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		MOO_DEBUG2 (moo, "Cannot modify file descriptor %d in epoll - %hs\n", fd, strerror(errno));
 		return -1;
 	}
@@ -1457,7 +1603,7 @@ static int vm_startup (moo_t* moo)
 	xtn->ep = open("/dev/poll", O_RDWR);
 	if (xtn->ep == -1) 
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		MOO_DEBUG1 (moo, "Cannot create devpoll - %hs\n", strerror(errno));
 		goto oops;
 	}
@@ -1473,7 +1619,7 @@ static int vm_startup (moo_t* moo)
 	#endif
 	if (xtn->ep == -1) 
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		MOO_DEBUG1 (moo, "Cannot create epoll - %hs\n", strerror(errno));
 		goto oops;
 	}
@@ -1499,7 +1645,7 @@ static int vm_startup (moo_t* moo)
 #if defined(USE_THREAD)
 	if (pipe(xtn->p) == -1)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		MOO_DEBUG1 (moo, "Cannot create pipes - %hs\n", strerror(errno));
 		goto oops;
 	}
@@ -2093,7 +2239,7 @@ static void vm_muxwait (moo_t* moo, const moo_ntime_t* dur, moo_vmprim_muxwait_c
 
 	if (n <= -1)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		MOO_DEBUG2 (moo, "Warning: multiplexer wait failure - %d, %s\n", errno, moo_geterrmsg(moo));
 	}
 	else
diff --git a/moo/lib/moo.h b/moo/lib/moo.h
index 71003b4..7fa6bfc 100644
--- a/moo/lib/moo.h
+++ b/moo/lib/moo.h
@@ -1069,16 +1069,18 @@ typedef void (*moo_log_write_t) (
 	moo_oow_t          len
 );
 
-typedef void (*moo_syserrstrb_t) (
+typedef moo_errnum_t (*moo_syserrstrb_t) (
 	moo_t*             moo,
-	int                syserr,
+	int                syserr_type,
+	int                syserr_code,
 	moo_bch_t*         buf,
 	moo_oow_t          len
 );
 
-typedef void (*moo_syserrstru_t) (
+typedef moo_errnum_t (*moo_syserrstru_t) (
 	moo_t*             moo,
-	int                syserr,
+	int                syserr_type,
+	int                syserr_code,
 	moo_uch_t*         buf,
 	moo_oow_t          len
 );
@@ -1794,7 +1796,8 @@ MOO_EXPORT void moo_seterrnum (
 
 MOO_EXPORT void moo_seterrwithsyserr (
 	moo_t* moo,
-	int    syserr
+	int    syserr_type,
+	int    syserr_code
 );
 
 MOO_EXPORT void moo_seterrbfmt (
@@ -2296,10 +2299,6 @@ MOO_EXPORT void moo_assertfailed (
 	moo_oow_t        line
 );
 
-MOO_EXPORT moo_errnum_t moo_syserr_to_errnum (
-	int syserr
-);
-
 MOO_EXPORT const moo_ooch_t* moo_errnum_to_errstr (
 	moo_errnum_t errnum
 );
diff --git a/moo/mod/sck.c b/moo/mod/sck.c
index 28a3fc7..7d5ba17 100644
--- a/moo/mod/sck.c
+++ b/moo/mod/sck.c
@@ -89,7 +89,7 @@ create_socket:
 			goto create_socket;
 		}
 #endif
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		goto oops;
 	}
 
@@ -110,7 +110,7 @@ create_socket:
 		if (fl == -1)
 		{
 		fcntl_failure:
-			moo_seterrwithsyserr (moo, errno);
+			moo_seterrwithsyserr (moo, 0, errno);
 			goto oops;
 		}
 
@@ -150,7 +150,7 @@ static moo_pfrc_t pf_close_socket (moo_t* moo, moo_mod_t* mod, moo_ooi_t nargs)
 		moo_releaseiohandle (moo, MOO_OOP_TO_SMOOI(sck->handle));
 		if (close(MOO_OOP_TO_SMOOI(sck->handle)) == -1)
 		{
-			moo_seterrwithsyserr (moo, errno);
+			moo_seterrwithsyserr (moo, 0, errno);
 			return MOO_PF_FAILURE;
 		}
 		else
@@ -191,7 +191,7 @@ static moo_pfrc_t pf_bind_socket (moo_t* moo, moo_mod_t* mod, moo_ooi_t nargs)
 	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &enable, MOO_SIZEOF(int)) == -1 ||
 	    bind(fd, (struct sockaddr*)MOO_OBJ_GET_BYTE_SLOT(arg), moo_sck_addr_len((sck_addr_t*)MOO_OBJ_GET_BYTE_SLOT(arg))) == -1)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		return MOO_PF_FAILURE;
 	}
 
@@ -231,7 +231,7 @@ static moo_pfrc_t pf_accept_socket (moo_t* moo, moo_mod_t* mod, moo_ooi_t nargs)
 		
 		if (errno != EWOULDBLOCK && errno != EAGAIN) 
 		{
-			moo_seterrwithsyserr (moo, errno);
+			moo_seterrwithsyserr (moo, 0, errno);
 			return MOO_PF_FAILURE;
 		}
 
@@ -251,7 +251,7 @@ normal_accept:
 	{
 		if (errno != EWOULDBLOCK && errno != EAGAIN)
 		{
-			moo_seterrwithsyserr (moo, errno);
+			moo_seterrwithsyserr (moo, 0, errno);
 			return MOO_PF_FAILURE;
 		}
 
@@ -264,7 +264,7 @@ normal_accept:
 	if (fl == -1)
 	{
 	fcntl_failure:
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		close (newfd);
 		return MOO_PF_FAILURE;
 	}
@@ -339,7 +339,7 @@ static moo_pfrc_t pf_listen_socket (moo_t* moo, moo_mod_t* mod, moo_ooi_t nargs)
 	n = listen(fd, MOO_OOP_TO_SMOOI(arg));
 	if (n == -1)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		return MOO_PF_FAILURE;
 	}
 
@@ -381,7 +381,7 @@ static moo_pfrc_t pf_connect_socket (moo_t* moo, moo_mod_t* mod, moo_ooi_t nargs
 		}
 		else
 		{
-			moo_seterrwithsyserr (moo, errno);
+			moo_seterrwithsyserr (moo, 0, errno);
 			return MOO_PF_FAILURE;
 		}
 	}
@@ -413,7 +413,7 @@ static moo_pfrc_t pf_get_socket_error (moo_t* moo, moo_mod_t* mod, moo_ooi_t nar
 	len = MOO_SIZEOF(ret);
 	if (getsockopt(fd, SOL_SOCKET, SO_ERROR, (char*)&ret, &len) == -1)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		return MOO_PF_FAILURE;
 	}
 
@@ -484,7 +484,7 @@ static moo_pfrc_t pf_read_socket (moo_t* moo, moo_mod_t* mod, moo_ooi_t nargs)
 	n = recv(fd, &MOO_OBJ_GET_BYTE_SLOT(buf)[offset], length, 0);
 	if (n <= -1 && errno != EWOULDBLOCK && errno != EAGAIN)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		return MOO_PF_FAILURE;
 	}
 
@@ -557,7 +557,7 @@ static moo_pfrc_t pf_write_socket (moo_t* moo, moo_mod_t* mod, moo_ooi_t nargs)
 	n = send(fd, &MOO_OBJ_GET_BYTE_SLOT(buf)[offset], length, 0);
 	if (n <= -1 && errno != EWOULDBLOCK && errno != EAGAIN)
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		return MOO_PF_FAILURE;
 	}
 
diff --git a/moo/mod/stdio.c b/moo/mod/stdio.c
index 6ce108f..b96d973 100644
--- a/moo/mod/stdio.c
+++ b/moo/mod/stdio.c
@@ -75,7 +75,7 @@ static moo_pfrc_t pf_open (moo_t* moo, moo_mod_t* mod, moo_ooi_t nargs)
 #endif
 	if (!stdio->fp) 
 	{
-		moo_seterrwithsyserr (moo, errno);
+		moo_seterrwithsyserr (moo, 0, errno);
 		goto softfail;
 	}
 
@@ -157,7 +157,7 @@ static moo_pfrc_t __pf_puts (moo_t* moo, moo_ooi_t nargs, moo_oow_t limit)
 
 				if (fwrite (bcs, 1, bcslen, stdio->fp) < bcslen)
 				{
-					moo_seterrwithsyserr (moo, errno);
+					moo_seterrwithsyserr (moo, 0, errno);
 					goto softfail;
 				}
 
@@ -169,7 +169,7 @@ static moo_pfrc_t __pf_puts (moo_t* moo, moo_ooi_t nargs, moo_oow_t limit)
 		puts_string:
 			if (fwrite (x->slot, 1, MOO_OBJ_GET_SIZE(x), stdio->fp) < MOO_OBJ_GET_SIZE(x))
 			{
-				moo_seterrwithsyserr (moo, errno);
+				moo_seterrwithsyserr (moo, 0, errno);
 				goto softfail;
 			}
 		#endif