diff --git a/.vscode/c_cpp_properties.json b/.vscode/c_cpp_properties.json
index a784916d..645cfa18 100644
--- a/.vscode/c_cpp_properties.json
+++ b/.vscode/c_cpp_properties.json
@@ -9,8 +9,9 @@
             "cStandard": "c99",
             "cppStandard": "c++98",
             "intelliSenseMode": "linux-clang-x86",
-            "compilerPath": ""
+            "compilerPath": "",
+            "configurationProvider": "ms-vscode.makefile-tools"
         }
     ],
     "version": 4
-}
+}
\ No newline at end of file
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 46e0a2b2..80c6ee7a 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -57,7 +57,8 @@
     "gxpriv.h": "c",
     "osfastcast.h": "c",
     "osfont.h": "c",
-    "arq.h": "c"
+    "arq.h": "c",
+    "string.h": "c"
   },
   "files.autoSave": "onFocusChange",
   "files.insertFinalNewline": true,
diff --git a/configure.py b/configure.py
index bb6af526..f664fa79 100755
--- a/configure.py
+++ b/configure.py
@@ -872,15 +872,15 @@ LIBS = [
             ["Runtime/file_io", True],
             ["Runtime/errno", True],
             ["Runtime/FILE_POS", True],
-            "Runtime/mbstring",
+            ["Runtime/mbstring", True],
             ["Runtime/mem", True],
             ["Runtime/mem_funcs", True],
             ["Runtime/misc_io", True],
             "Runtime/printf",
             ["Runtime/qsort", False],
             ["Runtime/rand", True],
-            "Runtime/sscanf",
-            "Runtime/string",
+            ["Runtime/sscanf", True],
+            ["Runtime/string", True],
             ["Runtime/float", True],
             "Runtime/strtold",
             ["Runtime/uart_console_io", True],
diff --git a/libc/errno.h b/libc/errno.h
index 982e8ec2..f06a6615 100644
--- a/libc/errno.h
+++ b/libc/errno.h
@@ -10,8 +10,9 @@ extern int errno;
 #define ENOERR 0
 #define EDOM 33
 #define ERANGE 34
-#define EFPOS 40
 #define ESIGPARM 36
+#define EFPOS 40
+#define	EILSEQ		84
 
 #ifdef __cplusplus
 }
diff --git a/libc/stdio.h b/libc/stdio.h
index 7fb47db7..9937d4d0 100644
--- a/libc/stdio.h
+++ b/libc/stdio.h
@@ -99,6 +99,21 @@ typedef struct _IO_FILE {
   struct _IO_FILE* next_file_struct;
 } FILE;
 
+typedef struct {
+  char* CharStr;
+  size_t MaxCharCount;
+  size_t CharsWritten;
+} __OutStrCtrl;
+
+typedef struct {
+  char* NextChar;
+  int NullCharDetected;
+} __InStrCtrl;
+
+#define EOF	-1L
+
+enum __ReadProcActions { __GetChar, __UngetChar, __CheckForError };
+
 #define _IONBF 0
 #define _IOLBF 1
 #define _IOFBF 2
@@ -110,7 +125,7 @@ int vprintf(const char* format, va_list arg);
 int vsprintf(char* s, const char* format, va_list arg);
 size_t fread(const void*, size_t memb_size, size_t num_memb, FILE*);
 size_t fwrite(const void*, size_t memb_size, size_t num_memb, FILE*);
-int fseek(FILE * file, long offset, int mode);
+int fseek(FILE* file, long offset, int mode);
 size_t __fwrite(const void*, size_t, size_t, FILE*);
 
 #ifdef __cplusplus
diff --git a/src/Runtime/mbstring.c b/src/Runtime/mbstring.c
new file mode 100644
index 00000000..a7819ee3
--- /dev/null
+++ b/src/Runtime/mbstring.c
@@ -0,0 +1,116 @@
+#include "errno.h"
+#include "stdio.h"
+#include "string.h"
+#include "wstring.h"
+
+#pragma ANSI_strict off
+
+#ifndef __WINT_TYPE__
+#define __WINT_TYPE__ unsigned int
+#endif
+
+typedef struct {
+  int __count;
+  union {
+    __WINT_TYPE__ __wch;
+    char __wchb[4];
+  } __value; /* Value so far.  */
+} mbstate_t;
+
+static int is_utf8_complete(const char* s, size_t n);
+static int is_utf8_complete(const char* s, size_t n) {
+  if (n <= 0) /* 0 or fewer characters do not form a valid multibyte character */
+    return (-1);
+
+  if (*s == 0x00)
+    return (0);
+
+  if ((*s & 0x80) == 0x00)
+    return (1);
+  else if ((*s & 0xe0) == 0xc0) /* need 2 bytes */
+    if (n >= 2)
+      if (((*(s + 1) & 0x80) == 0x80))
+        return (2);
+      else
+        return (-1);
+    else
+      return (-2);
+
+  else if ((*s & 0xf0) == 0xe0)
+    if (n >= 3)
+      if (((*(s + 1) & 0x80) == 0x80) && ((*(s + 2) & 0x80) == 0x80))
+        return (3);
+      else
+        return (-1);
+    else if (((n == 2) && ((*(s + 1) & 0x80) == 0x80)) || (n == 1))
+      return (-2);
+    else
+      return (-1);
+  else
+    return (-1);
+}
+
+#pragma dont_inline on
+static int unicode_to_UTF8(char* s, wchar_t wchar) {
+  int number_of_bytes;
+  wchar_t wide_char;
+  char* target_ptr;
+  char first_byte_mark[4] = {0x00, 0x00, 0xc0, 0xe0};
+
+  if (!s) {
+    return 0;
+  }
+
+  wide_char = wchar;
+  if (wide_char < 0x0080)
+    number_of_bytes = 1;
+  else if (wide_char < 0x0800)
+    number_of_bytes = 2;
+  else
+    number_of_bytes = 3;
+
+  target_ptr = s + number_of_bytes;
+
+  switch (number_of_bytes) {
+  case 3:
+    *--target_ptr = (wide_char & 0x003f) | 0x80;
+    wide_char >>= 6;
+  case 2:
+    *--target_ptr = (wide_char & 0x003f) | 0x80;
+    wide_char >>= 6;
+  case 1:
+    *--target_ptr = wide_char | first_byte_mark[number_of_bytes];
+  }
+
+  return (number_of_bytes);
+}
+#pragma dont_inline reset
+
+int wctomb(char* s, wchar_t wchar) { return (unicode_to_UTF8(s, wchar)); }
+
+size_t wcstombs(char* s, const wchar_t* pwcs, size_t n) {
+  int chars_written = 0;
+  int result;
+  char temp[3];
+  wchar_t* source;
+
+  if (!s || !pwcs)
+    return (0);
+
+  source = (wchar_t*)pwcs;
+  while (chars_written <= n) {
+    if (!*source) {
+      *(s + chars_written) = '\0';
+      break;
+    } else {
+      result = wctomb(temp, *source++);
+      if ((chars_written + result) <= n) {
+        strncpy(s + chars_written, temp, result);
+        chars_written += result;
+      } else
+        break;
+    }
+  }
+
+  return (chars_written);
+}
diff --git a/src/Runtime/sscanf.c b/src/Runtime/sscanf.c
new file mode 100644
index 00000000..171ee58b
--- /dev/null
+++ b/src/Runtime/sscanf.c
@@ -0,0 +1,26 @@
+#include "stdio.h"
+
+int __StringRead(void* isc, int ch, int Action) {
+  char ret;
+  __InStrCtrl* iscp = (__InStrCtrl*)isc;
+  switch (Action) {
+  case __GetChar:
+    ret = *(iscp->NextChar);
+    if (ret == '\0') {
+      iscp->NullCharDetected = 1;
+      return (EOF);
+    } else {
+      iscp->NextChar++;
+      return ((unsigned char)ret);
+    }
+  case __UngetChar:
+    if (!iscp->NullCharDetected)  
+      iscp->NextChar--;           
+    else                          
+      iscp->NullCharDetected = 0; 
+    return (ch);
+  case __CheckForError:
+    return (iscp->NullCharDetected);
+  }
+  return 0; 
+}
diff --git a/src/Runtime/string.c b/src/Runtime/string.c
new file mode 100644
index 00000000..82ca5688
--- /dev/null
+++ b/src/Runtime/string.c
@@ -0,0 +1,201 @@
+#include "string.h"
+
+size_t strlen(const char* str) {
+  size_t len = -1;
+  unsigned char* p = (unsigned char*)str - 1;
+  do {
+    len++;
+  } while (*++p);
+  return len;
+}
+
+char*(strcpy)(char* dst, const char* src) {
+  unsigned char *destb, *fromb;
+  unsigned int w, t, align;
+  unsigned int k1;
+  unsigned int k2;
+
+  fromb = (unsigned char*)src;
+  destb = (unsigned char*)dst;
+
+  if ((align = ((int)fromb & 3)) != ((int)destb & 3)) {
+    goto bytecopy;
+  }
+
+  if (align) {
+    if ((*destb = *fromb) == 0) {
+      return dst;
+    }
+
+    for (align = 3 - align; align; align--) {
+      if ((*(++destb) = *(++fromb)) == 0) {
+        return dst;
+      }
+    }
+    ++destb;
+    ++fromb;
+  }
+
+  k1 = 0x80808080;
+  k2 = 0xfefefeff;
+
+  w = *((int*)(fromb));
+  t = w + k2;
+  t &= k1;
+  if (t) {
+    goto bytecopy;
+  }
+
+  --((int*)(destb));
+
+  do {
+    *(++((int*)(destb))) = w;
+    w = *(++((int*)(fromb)));
+
+    t = w + k2;
+    t &= k1;
+    if (t)
+      goto adjust;
+  } while (1);
+
+adjust:
+  ++((int*)(destb));
+
+bytecopy:
+  if ((*destb = *fromb) == 0)
+    return (dst);
+  do {
+    if ((*(++destb) = *(++fromb)) == 0)
+      return dst;
+  } while (1);
+
+  return dst;
+}
+
+char* strncpy(char* dst, const char* src, size_t n) {
+  const unsigned char* p = (const unsigned char*)src - 1;
+  unsigned char* q = (unsigned char*)dst - 1;
+  unsigned char zero = 0;
+
+  n++;
+
+  while (--n)
+    if (!(*++q = *++p)) {
+      while (--n)
+        *++q = 0;
+      break;
+    }
+
+  return dst;
+}
+
+int strcmp(const char* str1, const char* str2) {
+  unsigned char* left = (unsigned char*)str1;
+  unsigned char* right = (unsigned char*)str2;
+  unsigned int k1, k2, align, l1, r1, x;
+
+  l1 = *left;
+  r1 = *right;
+  if (l1 - r1) {
+    return l1 - r1;
+  }
+
+  if ((align = ((int)left & 3)) != ((int)right & 3)) {
+    goto bytecopy;
+  }
+  if (align) {
+    if (l1 == 0) {
+      return 0;
+    }
+    for (align = 3 - align; align; align--) {
+      l1 = *(++left);
+      r1 = *(++right);
+      if (l1 - r1) {
+        return l1 - r1;
+      }
+      if (l1 == 0) {
+        return 0;
+      }
+    }
+    left++;
+    right++;
+  }
+
+  k1 = 0x80808080;
+  k2 = 0xfefefeff;
+
+  l1 = *(int*)left;
+  r1 = *(int*)right;
+  x = l1 + k2;
+  if (x & k1) {
+    goto adjust;
+  }
+  while (l1 == r1) {
+    l1 = *(++((int*)(left)));
+    r1 = *(++((int*)(right)));
+    x = l1 + k2;
+    if (x & k1) {
+      goto adjust;
+    }
+  }
+
+  if (l1 > r1) {
+    return 1;
+  }
+
+  return -1;
+
+adjust:
+  l1 = *left;
+  r1 = *right;
+  if (l1 - r1) {
+    return l1 - r1;
+  }
+
+bytecopy:
+  if (l1 == 0) {
+    return 0;
+  }
+
+  do {
+    l1 = *(++left);
+    r1 = *(++right);
+    if (l1 - r1) {
+      return l1 - r1;
+    }
+    if (l1 == 0) {
+      return 0;
+    }
+  } while (1);
+}
+
+int strncmp(const char* str1, const char* str2, size_t n) {
+  const unsigned char* p1 = (unsigned char*)str1 - 1;
+  const unsigned char* p2 = (unsigned char*)str2 - 1;
+  unsigned long c1, c2;
+
+  n++;
+
+  while (--n) {
+    if ((c1 = *++p1) != (c2 = *++p2)) {
+      return (c1 - c2);
+    } else if (!c1) {
+      break;
+    }
+  }
+
+  return 0;
+}
+
+char* strchr(const char* str, int chr) {
+  const unsigned char* p = (unsigned char*)str - 1;
+  unsigned long c = (chr & 0xff);
+  unsigned long ch;
+
+  while (ch = *++p) {
+    if (ch == c)
+      return ((char*)p);
+  }
+
+  return (c ? 0 : (char*)p);
+}