diff --git a/include/stdio.h b/include/stdio.h
index bf9161b81c770d247b9dd6f6e5c2059c2c419d42..eaeb879d39ee2b46a1dc7c9bc3d074701c290252 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -126,9 +126,10 @@ EXTERN int    sprintf(char *buf, const char *format, ...);
 EXTERN int    snprintf(char *buf, size_t size, const char *format, ...);
 
 EXTERN int    ungetc(int c, FILE *stream);
-EXTERN int    vprintf(const char *s, va_list ap);
-EXTERN int    vfprintf(FILE *stream, const char *s, va_list ap);
-EXTERN int    vsprintf(char *buf, const char *s, va_list ap);
+EXTERN int    vprintf(const char *format, va_list ap);
+EXTERN int    vfprintf(FILE *stream, const char *format, va_list ap);
+EXTERN int    vsprintf(char *buf, const char *format, va_list ap);
+EXTERN int    vsnprintf(char *buf, size_t size, const char *format, va_list ap);
 
 /* POSIX-like File System Interfaces */
 
diff --git a/lib/Makefile b/lib/Makefile
index 9200a3dc323fe991fc32348cceb8c0347efba672..5e9db3e6a61b877eba66cbc1d9593f48be78809c 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -54,8 +54,7 @@ STRING_SRCS	= lib_memset.c lib_memcpy.c lib_memcmp.c lib_memmove.c \
 CTYPE_SRCS	= 
 
 STDIO_SRCS	= lib_printf.c lib_rawprintf.c lib_lowprintf.c lib_sprintf.c lib_snprintf.c \
-		  lib_libsprintf.c lib_vsprintf.c lib_libvsprintf.c lib_memstream.c lib_lowstream.c \
-		  lib_nullstream.c lib_sscanf.c
+		  lib_libsprintf.c lib_vsprintf.c lib_vsnprintf.c lib_libvsprintf.c \ lib_memstream.c lib_lowstream.c lib_nullstream.c lib_sscanf.c
 
 ifneq ($(CONFIG_NFILE_DESCRIPTORS),0)
 STDIO_SRCS	+= lib_rawstream.c
diff --git a/lib/lib_vsnprintf.c b/lib/lib_vsnprintf.c
new file mode 100644
index 0000000000000000000000000000000000000000..5dba0cac299a4104600f9191f1e5ca800bf9f52d
--- /dev/null
+++ b/lib/lib_vsnprintf.c
@@ -0,0 +1,92 @@
+/************************************************************
+ * lib/lib_vsnprintf.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <stdio.h>
+#include "lib_internal.h"
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/************************************************************
+ * Private Type Declarations
+ ************************************************************/
+
+/************************************************************
+ * Private Function Prototypes
+ ************************************************************/
+
+/************************************************************
+ * Global Constant Data
+ ************************************************************/
+
+/************************************************************
+ * Global Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Constant Data
+ ************************************************************/
+
+/************************************************************
+ * Private Variables
+ ************************************************************/
+
+/************************************************************
+ * Global Functions
+ ************************************************************/
+
+/************************************************************
+ * sprintf
+ ************************************************************/
+
+int vsnprintf(char *buf, size_t size, const char *format, va_list ap)
+{
+  struct lib_memstream_s memstream;
+  int     n;
+
+  /* Initialize a memory stream to write to the buffer */
+
+  lib_memstream(&memstream, buf, size);
+
+  /* Then let lib_vsprintf do the real work */
+
+  n = lib_vsprintf(&memstream.public, format, ap);
+  return n;
+}