diff --git a/src/blitter/8bpp_simple.hpp b/src/blitter/8bpp_simple.hpp
--- a/src/blitter/8bpp_simple.hpp
+++ b/src/blitter/8bpp_simple.hpp
@@ -19,7 +19,7 @@
 class Blitter_8bppSimple FINAL : public Blitter_8bppBase {
 public:
 	/* virtual */ void Draw(Blitter::BlitterParams *bp, BlitterMode mode, ZoomLevel zoom);
-	/* virtual */ Sprite *Encode(SpriteLoader::Sprite *sprite, AllocatorProc *allocator);
+	/* virtual */ Sprite *Encode(const SpriteLoader::Sprite *sprite, AllocatorProc *allocator);
 
 	/* virtual */ const char *GetName() { return "8bpp-simple"; }
 };