diff --git a/mlibc/include/stdarg.h b/mlibc/include/stdarg.h
index 9ffcdf59..fa5a6332 100644
--- a/mlibc/include/stdarg.h
+++ b/mlibc/include/stdarg.h
@@ -43,6 +43,7 @@ typedef int va_list;
 #define va_copy(dest, src) dest = src
 
 int vprintf (char const* format, va_list ap);
+int vsprintf (char *str, char const *format, va_list ap);
 int vsnprintf (char *str, size_t size, char const *format, va_list ap);
 
 #endif // ! (__GNUC__ && POSIX)
diff --git a/mlibc/libc-gcc.c b/mlibc/libc-gcc.c
index 22fd2d8d..2a636e8a 100644
--- a/mlibc/libc-gcc.c
+++ b/mlibc/libc-gcc.c
@@ -389,10 +389,8 @@ printf (char const* format, ...)
 }
 
 int
-sprintf (char *str, char const* format, ...)
+vsprintf (char *str, char const* format, va_list ap)
 {
-  va_list ap;
-  va_start (ap, format);
   char const *p = format;
   while (*p)
     if (*p != '%')
@@ -411,8 +409,19 @@ sprintf (char *str, char const* format, ...)
           }
         p++;
       }
+
+  *str = 0;
+  return strlen (str);
+}
+
+int
+sprintf (char *str, char const* format, ...)
+{
+  va_list ap;
+  va_start (ap, format);
+  int r = vsprintf (str, format, ap);
   va_end (ap);
-  return 0;
+  return r;
 }
 #endif
 
diff --git a/mlibc/libc-mes+tcc.c b/mlibc/libc-mes+tcc.c
index 275aed2d..23d7da59 100644
--- a/mlibc/libc-mes+tcc.c
+++ b/mlibc/libc-mes+tcc.c
@@ -248,8 +248,11 @@ sigemptyset (sigset_t *set)
 int
 snprintf(char *str,  size_t size,  char const *format, ...)
 {
-  eputs ("snprintf stub\n");
-  return 0;
+  va_list ap;
+  va_start (ap, format);
+  int r = vsprintf (str, format, ap);
+  va_end (ap);
+  return r;
 }
 
 int
@@ -337,27 +340,7 @@ time_t time (time_t *tloc)
 int
 vsnprintf (char *str, size_t size, char const *format, va_list ap)
 {
-  char const *p = format;
-  while (*p)
-    if (*p != '%')
-      *str++ = *p++;
-    else
-      {
-        p++;
-        char c = *p;
-        switch (c)
-          {
-          case '%': {*str++ = *p; break;}
-          case 'c': {char c; c = va_arg (ap, char); *str++=c; break;}
-          case 'd': {int d; d = va_arg (ap, int); strcpy (str, itoa (d)); break;}
-          case 's': {char *s; s = va_arg (ap, char *); strcpy (str, s); break;}
-          default: {*str++ = *p; break;}
-          }
-        p++;
-      }
-  va_end (ap);
-  *str = 0;
-  return strlen (str);
+  return vsprintf (str, format, ap);
 }
 
 void *
diff --git a/mlibc/libc-mes.c b/mlibc/libc-mes.c
index 154d1f4b..eee37500 100644
--- a/mlibc/libc-mes.c
+++ b/mlibc/libc-mes.c
@@ -416,10 +416,8 @@ printf (char const* format, ...)
 }
 
 int
-sprintf (char *str, char const* format, ...)
+vsprintf (char *str, char const* format, va_list ap)
 {
-  va_list ap;
-  va_start (ap, format);
   char const *p = format;
   while (*p)
     if (*p != '%')
@@ -439,5 +437,16 @@ sprintf (char *str, char const* format, ...)
         p++;
       }
   va_end (ap);
-  return 0;
+  *str = 0;
+  return strlen (str);
+}
+
+int
+sprintf (char *str, char const* format, ...)
+{
+  va_list ap;
+  va_start (ap, format);
+  int r = vsprintf (str, format, ap);
+  va_end (ap);
+  return r;
 }