diff --git a/src/blitter/null.cpp b/src/blitter/null.cpp
--- a/src/blitter/null.cpp
+++ b/src/blitter/null.cpp
@@ -12,6 +12,7 @@
 #include "../stdafx.h"
 #include "null.hpp"
 
+/** Instantiation of the null blitter factory. */
 static FBlitter_Null iFBlitter_Null;
 
 Sprite *Blitter_Null::Encode(SpriteLoader::Sprite *sprite, AllocatorProc *allocator)