diff --git a/userspace/libraries/LibC/stdlib.cpp b/userspace/libraries/LibC/stdlib.cpp
index 41317673..0cb34180 100644
--- a/userspace/libraries/LibC/stdlib.cpp
+++ b/userspace/libraries/LibC/stdlib.cpp
@@ -572,20 +572,21 @@ int mblen(const char* s, size_t n)
 
 size_t mbstowcs(wchar_t* __restrict pwcs, const char* __restrict s, size_t n)
 {
-	auto* us = reinterpret_cast<const unsigned char*>(s);
-
-	size_t len = 0;
+	size_t written = 0;
 
 	switch (__getlocale(LC_CTYPE))
 	{
 		case LOCALE_INVALID:
 			ASSERT_NOT_REACHED();
 		case LOCALE_POSIX:
-			while (*us && len < n)
-				pwcs[len++] = *us++;
+			if (pwcs == nullptr)
+				written = strlen(s);
+			else for (; s[written] && written < n; written++)
+				pwcs[written] = s[written];
 			break;
 		case LOCALE_UTF8:
-			while (*us && len < n)
+			const auto* us = reinterpret_cast<const unsigned char*>(s);
+			for (; *us && (pwcs == nullptr || written < n); written++)
 			{
 				auto wch = BAN::UTF8::to_codepoint(us);
 				if (wch == BAN::UTF8::invalid)
@@ -593,16 +594,57 @@ size_t mbstowcs(wchar_t* __restrict pwcs, const char* __restrict s, size_t n)
 					errno = EILSEQ;
 					return -1;
 				}
-				pwcs[len++] = wch;
+				if (pwcs != nullptr)
+					pwcs[written] = wch;
 				us += BAN::UTF8::byte_length(*us);
 			}
 			break;
 	}
 
-	if (len < n)
-		pwcs[len] = 0;
+	if (pwcs != nullptr && written < n)
+		pwcs[written] = L'\0';
+	return written;
+}
 
-	return len;
+size_t wcstombs(char* __restrict s, const wchar_t* __restrict pwcs, size_t n)
+{
+	size_t written = 0;
+
+	switch (__getlocale(LC_CTYPE))
+	{
+		case locale_t::LOCALE_INVALID:
+			ASSERT_NOT_REACHED();
+		case locale_t::LOCALE_POSIX:
+			for (size_t i = 0; pwcs[i] && (s == nullptr || written < n); i++)
+			{
+				if (pwcs[i] > 0xFF)
+					return -1;
+				if (s != nullptr)
+					s[written] = pwcs[i];
+				written++;
+			}
+			break;
+		case locale_t::LOCALE_UTF8:
+			for (size_t i = 0; pwcs[i] && (s == nullptr || written < n); i++)
+			{
+				char buffer[5];
+				if (!BAN::UTF8::from_codepoints(pwcs + i, 1, buffer))
+					return -1;
+
+				const size_t len = strlen(buffer);
+				if (written + len > n)
+					return len;
+
+				if (s != nullptr)
+					memcpy(s + written, buffer, len);
+				written += len;
+			}
+			break;
+	}
+
+	if (s && written < n)
+		s[written] = '\0';
+	return written;
 }
 
 void* bsearch(const void* key, const void* base, size_t nel, size_t width, int (*compar)(const void*, const void*))