Fix typos & Co
diff --git a/programs/pkey/key_app_writer.c b/programs/pkey/key_app_writer.c
index 1be0dd3..b0efa08 100644
--- a/programs/pkey/key_app_writer.c
+++ b/programs/pkey/key_app_writer.c
@@ -404,4 +404,4 @@
 
     return( ret );
 }
-#endif /* POLARSSL_X509_WRITE_C && POLARSSL_FS_IO */
+#endif /* POLARSSL_PK_WRITE_C && POLARSSL_FS_IO */