diff --git a/libc/libc.h b/libc/libc.h
index 4410401338..023049531b 100644
--- a/libc/libc.h
+++ b/libc/libc.h
@@ -53,6 +53,7 @@
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
+
 /* This configuration directory is used in environment variable processing
  * when we need to reference the user's home directory.  There are no user
  * directories in NuttX so, by default, this always refers to the root
diff --git a/tools/mkconfig.c b/tools/mkconfig.c
index 579e29df00..15c4c87c91 100644
--- a/tools/mkconfig.c
+++ b/tools/mkconfig.c
@@ -205,8 +205,10 @@ int main(int argc, char **argv, char **envp)
   printf(" * support is disabled\n");
   printf(" */\n\n");
   printf("#if CONFIG_NFILE_STREAMS == 0\n");
-  printf("#  undef CONFIG_STDIO_BUFFER_SIZE\n");
-  printf("#  define CONFIG_STDIO_BUFFER_SIZE 0\n");
+  printf("#  undef  CONFIG_STDIO_BUFFER_SIZE\n");
+  printf("#  undef  CONFIG_STDIO_LINEBUFFER\n");
+  printf("#  undef  CONFIG_STDIO_DISABLE_BUFFERING\n");
+  printf("#  define CONFIG_STDIO_DISABLE_BUFFERING 1\n");
   printf("#endif\n\n");
 
   printf("/* If the maximum message size is zero, then we assume that message queues\n");