diff --git a/libc/Makefile b/libc/Makefile
index c58ef40f..0ef66759 100644
--- a/libc/Makefile
+++ b/libc/Makefile
@@ -80,6 +80,7 @@ localtime.o \
localtime_r.o \
mbrtowc.o \
mbsrtowcs.o \
+mbstowcs.o \
mbtowc.o \
memccpy.o \
memchr.o \
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 48427457..0ddf5476 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -81,6 +81,7 @@ ldiv_t ldiv(long, long);
long long llabs(long long);
lldiv_t lldiv(long long, long long);
void* malloc(size_t);
+size_t mbstowcs(wchar_t* restrict, const char* restrict, size_t);
int mbtowc(wchar_t *restrict, const char* restrict, size_t);
#if !defined(_SORTIX_SOURCE)
char* mktemp(char* templ);
@@ -131,7 +132,6 @@ char* l64a(long);
void lcong48(unsigned short [7]);
long lrand48(void);
int mblen(const char*, size_t);
-size_t mbstowcs(wchar_t *restrict, const char* restrict, size_t);
char* mkdtemp(char*);
int mkstemp(char*);
long mrand48(void);
diff --git a/libc/mbstowcs.cpp b/libc/mbstowcs.cpp
new file mode 100644
index 00000000..e5ed34d2
--- /dev/null
+++ b/libc/mbstowcs.cpp
@@ -0,0 +1,38 @@
+/*******************************************************************************
+
+ Copyright(C) Jonas 'Sortie' Termansen 2013.
+
+ This file is part of the Sortix C Library.
+
+ The Sortix C Library is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or (at your
+ option) any later version.
+
+ The Sortix C Library is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with the Sortix C Library. If not, see .
+
+ mbstowcs.cpp
+ Convert a multibyte string to a wide-character string.
+
+*******************************************************************************/
+
+#include
+#include
+
+extern "C" size_t mbstowcs(wchar_t* dst, const char* src, size_t n)
+{
+ // Reset the secret conversion state variable in mbsrtowcs that is used when
+ // ps is NULL by successfully converting the empty string. As always, this
+ // is not multithread secure. For some reason, the standards don't mandate
+ // that the conversion state is reset when mbsrtowcs is called with ps=NULL,
+ // which arguably is a feature - but this function is supposed to do it.
+ const char* empty_string = "";
+ mbsrtowcs(NULL, &empty_string, 0, NULL);
+ return mbsrtowcs(dst, &src, n, NULL);
+}