diff --git a/libs/main/core/pistring.cpp b/libs/main/core/pistring.cpp
index 36a4ea5e..2448e0ed 100644
--- a/libs/main/core/pistring.cpp
+++ b/libs/main/core/pistring.cpp
@@ -27,7 +27,9 @@
 #ifdef WINDOWS
 #  include <stringapiset.h>
 #endif
-#include <wchar.h>
+#include <string>
+#include <locale>
+#include <codecvt>
 
 //! \addtogroup Core
 //! \{
@@ -197,11 +199,11 @@ llong PIString::toNumberBase(const PIString & value, int base, bool * ok) {
 void PIString::appendFromChars(const char * c, int s, const char * codepage) {
 	if (s == 0) return;
 	int old_sz = size_s();
+	if (s == -1) s = strlen(c);
 #ifdef PIP_ICU
 	UErrorCode e((UErrorCode)0);
 	UConverter * cc = ucnv_open(codepage, &e);
 	if (cc) {
-		if (s == -1) s = strlen(c);
 		d.enlarge(s);
 		e = (UErrorCode)0;
 		int sz = ucnv_toUChars(cc, (UChar*)(d.data(old_sz)), s, c, s, &e);
@@ -211,31 +213,15 @@ void PIString::appendFromChars(const char * c, int s, const char * codepage) {
 	}
 #else
 #  ifdef WINDOWS
-	if (s == -1) s = strlen(c);
 	int sz = MultiByteToWideChar((uint)(uintptr_t)codepage, MB_ERR_INVALID_CHARS, c, s, 0, 0);
 	if (sz <= 0) return;
 	d.enlarge(sz);
 	MultiByteToWideChar((uint)(uintptr_t)codepage, MB_ERR_INVALID_CHARS, c, s, (LPWSTR)d.data(old_sz), sz);
-	return;
 #  else
-	mbstate_t state;
-	memset(&state, 0, sizeof(state));
-	const char ** pc;
-	char * c_ = nullptr;
-	if (s > 0) {
-		c_ = (char*)malloc(s+1);
-		memcpy(c_, c, s);
-		c_[s] = '\0';
-		pc = (const char **)&c_;
-	} else {
-		pc = &c;
-	}
-	size_t len = mbsrtowcs(NULL, pc, 0, &state);
-	wchar_t wstr[len+1];
-	mbsrtowcs(&wstr[0], pc, len+1, &state);
-	if (c_) free(c_);
-	d.enlarge(len);
-	for (size_t i=0; i<len; ++i) d[old_sz+i] = PIChar(wstr[i]);
+	std::wstring_convert<std::codecvt_utf8<char16_t>, char16_t> ucs2conv;
+	std::u16string ucs2 = ucs2conv.from_bytes(c, c+s);
+	enlarge(ucs2.size());
+	ucs2.copy((char16_t *)PIDeque<PIChar>::data(old_sz), ucs2.size());
 #  endif
 #endif
 }
@@ -350,18 +336,10 @@ void PIString::buildData(const char * cp) const {
 	data_[sz] = '\0';
 	return;
 #  else
-	wchar_t wc;
-	mbstate_t state;
-	memset(&state, 0, sizeof(state));
-	data_ = (char *)malloc(MB_CUR_MAX*size()+1);
-	char *p = data_;
-	for (int i = 0; i < d.size_s(); ++i) {
-		wc = at(i).toWChar();
-		sz = wcrtomb(p, wc, &state);
-		if (sz < 0) break;
-		p += sz;
-	}
-	p[0] = '\0';
+	std::wstring_convert<std::codecvt_utf8<char16_t>, char16_t> ucs2conv;
+	std::string u8str = ucs2conv.to_bytes((char16_t*)PIDeque<PIChar>::data(), (char16_t*)PIDeque<PIChar>::data()+size());
+	data_ = (char *)malloc(u8str.size()+1);
+	strcpy(data_, u8str.c_str());
 #  endif
 #endif
 }