diff --git a/include/nuttx/fs/fs.h b/include/nuttx/fs/fs.h
index fed454fc7d2..651f94ebabb 100644
--- a/include/nuttx/fs/fs.h
+++ b/include/nuttx/fs/fs.h
@@ -527,19 +527,19 @@ struct file_struct
   cookie_io_functions_t   fs_iofunc;    /* Callbacks to user / system functions */
   FAR void               *fs_cookie;    /* Pointer to file descriptor / cookie struct */
 #ifndef CONFIG_STDIO_DISABLE_BUFFERING
-  FAR unsigned char      *fs_bufstart;  /* Pointer to start of buffer */
-  FAR unsigned char      *fs_bufend;    /* Pointer to 1 past end of buffer */
-  FAR unsigned char      *fs_bufpos;    /* Current position in buffer */
-  FAR unsigned char      *fs_bufread;   /* Pointer to 1 past last buffered read char. */
+  FAR char               *fs_bufstart;  /* Pointer to start of buffer */
+  FAR char               *fs_bufend;    /* Pointer to 1 past end of buffer */
+  FAR char               *fs_bufpos;    /* Current position in buffer */
+  FAR char               *fs_bufread;   /* Pointer to 1 past last buffered read char. */
 #  if CONFIG_STDIO_BUFFER_SIZE > 0
-  unsigned char           fs_buffer[CONFIG_STDIO_BUFFER_SIZE];
+  char                    fs_buffer[CONFIG_STDIO_BUFFER_SIZE];
 #  endif
 #endif
   uint16_t                fs_oflags;    /* Open mode flags */
   uint8_t                 fs_flags;     /* Stream flags */
 #if CONFIG_NUNGET_CHARS > 0
   uint8_t                 fs_nungotten; /* The number of characters buffered for ungetc */
-  unsigned char           fs_ungotten[CONFIG_NUNGET_CHARS];
+  char                    fs_ungotten[CONFIG_NUNGET_CHARS];
 #endif
 };
 
diff --git a/libs/libc/stdio/lib_getdelim.c b/libs/libc/stdio/lib_getdelim.c
index 4b170280656..46c3acd2c82 100644
--- a/libs/libc/stdio/lib_getdelim.c
+++ b/libs/libc/stdio/lib_getdelim.c
@@ -121,7 +121,7 @@ ssize_t getdelim(FAR char **lineptr, size_t *n, int delimiter,
   dest = *lineptr;
   if (dest == NULL)
     {
-      dest = (FAR char *)lib_malloc(bufsize);
+      dest = lib_malloc(bufsize);
       if (dest == NULL)
         {
           ret = ENOMEM;
@@ -156,7 +156,7 @@ ssize_t getdelim(FAR char **lineptr, size_t *n, int delimiter,
            */
 
           bufsize  += BUFSIZE_INCR;
-          newbuffer = (FAR char *)lib_realloc(*lineptr, bufsize);
+          newbuffer = lib_realloc(*lineptr, bufsize);
           if (newbuffer == NULL)
             {
               ret = ENOMEM;
diff --git a/libs/libc/stdio/lib_libfflush.c b/libs/libc/stdio/lib_libfflush.c
index 4502ca31d10..94a8c37a661 100644
--- a/libs/libc/stdio/lib_libfflush.c
+++ b/libs/libc/stdio/lib_libfflush.c
@@ -102,7 +102,7 @@ ssize_t lib_fflush_unlocked(FAR FILE *stream, bool bforce)
 
       /* Try to write that amount */
 
-      src = (FAR const char *)stream->fs_bufstart;
+      src = stream->fs_bufstart;
       do
         {
           /* Perform the write */
diff --git a/libs/libc/stdio/lib_libfread_unlocked.c b/libs/libc/stdio/lib_libfread_unlocked.c
index 2c5e8bcb385..9b56854e3d0 100644
--- a/libs/libc/stdio/lib_libfread_unlocked.c
+++ b/libs/libc/stdio/lib_libfread_unlocked.c
@@ -229,7 +229,7 @@ ssize_t lib_fread_unlocked(FAR void *ptr, size_t count, FAR FILE *stream)
                         {
                           bytes_read = stream->fs_iofunc.read(
                                               stream->fs_cookie,
-                                              (FAR char *)stream->fs_bufread,
+                                              stream->fs_bufread,
                                               buffer_available);
                         }
                       else
diff --git a/libs/libc/stdio/lib_libvsprintf.c b/libs/libc/stdio/lib_libvsprintf.c
index 2f13334f5c2..5933ba77139 100644
--- a/libs/libc/stdio/lib_libvsprintf.c
+++ b/libs/libc/stdio/lib_libvsprintf.c
@@ -166,9 +166,9 @@ static int vsprintf_internal(FAR struct lib_outstream_s *stream,
   union
   {
 #if defined (CONFIG_LIBC_LONG_LONG) || (ULONG_MAX > 4294967295UL)
-    unsigned char __buf[22]; /* Size for -1 in octal, without '\0' */
+    char __buf[22]; /* Size for -1 in octal, without '\0' */
 #else
-    unsigned char __buf[11]; /* Size for -1 in octal, without '\0' */
+    char __buf[11]; /* Size for -1 in octal, without '\0' */
 #endif
 #ifdef CONFIG_LIBC_FLOATINGPOINT
     struct dtoa_s __dtoa;
@@ -860,7 +860,7 @@ flt_oper:
                 }
 
               stream_putc(ndigs, stream);
-              c = __ultoa_invert(exp, (FAR char *)buf, 10) - (FAR char *)buf;
+              c = __ultoa_invert(exp, buf, 10) - buf;
 
               if (exp >= 0 && exp <= 9)
                 {
@@ -904,7 +904,7 @@ flt_oper:
 #else
           buf[0] = va_arg(ap, int);
 #endif
-          pnt = (FAR char *)buf;
+          pnt = buf;
           size = 1;
           goto str_lpad;
 
@@ -913,7 +913,7 @@ flt_oper:
 #ifdef CONFIG_LIBC_NUMBERED_ARGS
           if ((flags & FL_ARGNUMBER) != 0)
             {
-              pnt = (FAR char *)arglist[argnumber - 1].value.cp;
+              pnt = arglist[argnumber - 1].value.cp;
             }
           else
             {
@@ -1028,7 +1028,7 @@ str_lpad:
 #if !defined(CONFIG_LIBC_LONG_LONG) && defined(CONFIG_HAVE_LONG_LONG)
               DEBUGASSERT(x >= 0 && x <= ULONG_MAX);
 #endif
-              c = __ultoa_invert(x, (FAR char *)buf, 10) - (FAR char *)buf;
+              c = __ultoa_invert(x, buf, 10) - buf;
             }
         }
       else
@@ -1204,7 +1204,7 @@ str_lpad:
 #if !defined(CONFIG_LIBC_LONG_LONG) && defined(CONFIG_HAVE_LONG_LONG)
               DEBUGASSERT(x <= ULONG_MAX);
 #endif
-              c = __ultoa_invert(x, (FAR char *)buf, base) - (FAR char *)buf;
+              c = __ultoa_invert(x, buf, base) - buf;
             }
 
           flags &= ~FL_NEGATIVE;
diff --git a/libs/libc/stdio/lib_setvbuf.c b/libs/libc/stdio/lib_setvbuf.c
index a0cbd9c4d60..0277cfdd210 100644
--- a/libs/libc/stdio/lib_setvbuf.c
+++ b/libs/libc/stdio/lib_setvbuf.c
@@ -77,7 +77,7 @@
 int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
 {
 #ifndef CONFIG_STDIO_DISABLE_BUFFERING
-  FAR unsigned char *newbuf = NULL;
+  FAR char *newbuf = NULL;
   uint8_t flags;
   int errcode;
 
@@ -174,7 +174,7 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
 
             if (buffer != NULL)
               {
-                newbuf = (FAR unsigned char *)buffer;
+                newbuf = buffer;
 
                 /* Indicate that we have an I/O buffer managed by the caller
                  * of setvbuf.
@@ -184,7 +184,7 @@ int setvbuf(FAR FILE *stream, FAR char *buffer, int mode, size_t size)
               }
             else
               {
-                newbuf = (FAR unsigned char *)lib_malloc(size);
+                newbuf = lib_malloc(size);
                 if (newbuf == NULL)
                   {
                     errcode = ENOMEM;
diff --git a/libs/libc/stdio/lib_sprintf.c b/libs/libc/stdio/lib_sprintf.c
index 4c7cee096d4..d99840a815d 100644
--- a/libs/libc/stdio/lib_sprintf.c
+++ b/libs/libc/stdio/lib_sprintf.c
@@ -41,14 +41,12 @@ int sprintf(FAR char *buf, FAR const IPTR char *fmt, ...)
 
   /* Initialize a memory stream to write to the buffer */
 
-  lib_memoutstream((FAR struct lib_memoutstream_s *)&memoutstream, buf,
-                    LIB_BUFLEN_UNKNOWN);
+  lib_memoutstream(&memoutstream, buf, LIB_BUFLEN_UNKNOWN);
 
   /* Then let lib_vsprintf do the real work */
 
   va_start(ap, fmt);
-  n = lib_vsprintf((FAR struct lib_outstream_s *)&memoutstream.common,
-                   fmt, ap);
+  n = lib_vsprintf(&memoutstream.common, fmt, ap);
   va_end(ap);
   return n;
 }
diff --git a/libs/libc/stdio/lib_vasprintf.c b/libs/libc/stdio/lib_vasprintf.c
index bdac04a4871..efaed060aac 100644
--- a/libs/libc/stdio/lib_vasprintf.c
+++ b/libs/libc/stdio/lib_vasprintf.c
@@ -84,13 +84,13 @@ int vasprintf(FAR char **ptr, FAR const IPTR char *fmt, va_list ap)
    */
 
   lib_nulloutstream(&nulloutstream);
-  lib_vsprintf((FAR struct lib_outstream_s *)&nulloutstream, fmt, ap);
+  lib_vsprintf(&nulloutstream, fmt, ap);
 
   /* Then allocate a buffer to hold that number of characters, adding one
    * for the null terminator.
    */
 
-  buf = (FAR char *)lib_malloc(nulloutstream.nput + 1);
+  buf = lib_malloc(nulloutstream.nput + 1);
   if (!buf)
     {
 #ifdef va_copy
@@ -104,18 +104,15 @@ int vasprintf(FAR char **ptr, FAR const IPTR char *fmt, va_list ap)
    * null terminator and will not report this in the number of output bytes.
    */
 
-  lib_memoutstream((FAR struct lib_memoutstream_s *)&memoutstream,
-                   buf, nulloutstream.nput + 1);
+  lib_memoutstream(&memoutstream, buf, nulloutstream.nput + 1);
 
   /* Then let lib_vsprintf do it's real thing */
 
 #ifdef va_copy
-  nbytes = lib_vsprintf((FAR struct lib_outstream_s *)&memoutstream.common,
-                        fmt, ap2);
+  nbytes = lib_vsprintf(&memoutstream.common, fmt, ap2);
   va_end(ap2);
 #else
-  nbytes = lib_vsprintf((FAR struct lib_outstream_s *)&memoutstream.common,
-                        fmt, ap);
+  nbytes = lib_vsprintf(&memoutstream.common, fmt, ap);
 #endif
 
   /* Return a pointer to the string to the caller.  NOTE: the memstream put()
diff --git a/libs/libc/stdio/lib_vsprintf.c b/libs/libc/stdio/lib_vsprintf.c
index 8bd1e18c113..08378f7f085 100644
--- a/libs/libc/stdio/lib_vsprintf.c
+++ b/libs/libc/stdio/lib_vsprintf.c
@@ -44,8 +44,6 @@ int vsprintf(FAR char *dest, FAR const IPTR char *src, va_list ap)
    * libs/libc/stdio/lib_vsprintf do the work.
    */
 
-  lib_memoutstream((FAR struct lib_memoutstream_s *)&memoutstream, dest,
-                   LIB_BUFLEN_UNKNOWN);
-  return lib_vsprintf((FAR struct lib_outstream_s *)&memoutstream.common,
-                      src, ap);
+  lib_memoutstream(&memoutstream, dest, LIB_BUFLEN_UNKNOWN);
+  return lib_vsprintf(&memoutstream.common, src, ap);
 }
diff --git a/libs/libc/stdio/lib_vsscanf.c b/libs/libc/stdio/lib_vsscanf.c
index d6a22307c92..5b53a9e0212 100644
--- a/libs/libc/stdio/lib_vsscanf.c
+++ b/libs/libc/stdio/lib_vsscanf.c
@@ -45,12 +45,10 @@ int vsscanf(FAR const char *buf, FAR const IPTR char *fmt, va_list ap)
 
   /* Initialize a memory stream to freadm from the buffer */
 
-  lib_meminstream((FAR struct lib_meminstream_s *)&meminstream, buf,
-                  LIB_BUFLEN_UNKNOWN);
+  lib_meminstream(&meminstream, buf, LIB_BUFLEN_UNKNOWN);
 
   /* Then let lib_vscanf do the real work */
 
-  n = lib_vscanf((FAR struct lib_instream_s *)&meminstream.common, NULL,
-                 fmt, ap);
+  n = lib_vscanf(&meminstream.common, NULL, fmt, ap);
   return n;
 }