diff --git a/src/blitter/null.hpp b/src/blitter/null.hpp
--- a/src/blitter/null.hpp
+++ b/src/blitter/null.hpp
@@ -17,31 +17,31 @@
 /** Blitter that does nothing. */
 class Blitter_Null : public Blitter {
 public:
-	/* virtual */ uint8 GetScreenDepth() { return 0; }
-	/* virtual */ void Draw(Blitter::BlitterParams *bp, BlitterMode mode, ZoomLevel zoom) {};
-	/* virtual */ void DrawColourMappingRect(void *dst, int width, int height, PaletteID pal) {};
-	/* virtual */ Sprite *Encode(const SpriteLoader::Sprite *sprite, AllocatorProc *allocator);
-	/* virtual */ void *MoveTo(void *video, int x, int y) { return NULL; };
-	/* virtual */ void SetPixel(void *video, int x, int y, uint8 colour) {};
-	/* virtual */ void DrawRect(void *video, int width, int height, uint8 colour) {};
-	/* virtual */ void DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash) {};
-	/* virtual */ void CopyFromBuffer(void *video, const void *src, int width, int height) {};
-	/* virtual */ void CopyToBuffer(const void *video, void *dst, int width, int height) {};
-	/* virtual */ void CopyImageToBuffer(const void *video, void *dst, int width, int height, int dst_pitch) {};
-	/* virtual */ void ScrollBuffer(void *video, int &left, int &top, int &width, int &height, int scroll_x, int scroll_y) {};
-	/* virtual */ int BufferSize(int width, int height) { return 0; };
-	/* virtual */ void PaletteAnimate(const Palette &palette) { };
-	/* virtual */ Blitter::PaletteAnimation UsePaletteAnimation() { return Blitter::PALETTE_ANIMATION_NONE; };
+	uint8 GetScreenDepth() override { return 0; }
+	void Draw(Blitter::BlitterParams *bp, BlitterMode mode, ZoomLevel zoom) override {};
+	void DrawColourMappingRect(void *dst, int width, int height, PaletteID pal) override {};
+	Sprite *Encode(const SpriteLoader::Sprite *sprite, AllocatorProc *allocator) override;
+	void *MoveTo(void *video, int x, int y) override { return NULL; };
+	void SetPixel(void *video, int x, int y, uint8 colour) override {};
+	void DrawRect(void *video, int width, int height, uint8 colour) override {};
+	void DrawLine(void *video, int x, int y, int x2, int y2, int screen_width, int screen_height, uint8 colour, int width, int dash) override {};
+	void CopyFromBuffer(void *video, const void *src, int width, int height) override {};
+	void CopyToBuffer(const void *video, void *dst, int width, int height) override {};
+	void CopyImageToBuffer(const void *video, void *dst, int width, int height, int dst_pitch) override {};
+	void ScrollBuffer(void *video, int &left, int &top, int &width, int &height, int scroll_x, int scroll_y) override {};
+	int BufferSize(int width, int height) override { return 0; };
+	void PaletteAnimate(const Palette &palette) override { };
+	Blitter::PaletteAnimation UsePaletteAnimation() override { return Blitter::PALETTE_ANIMATION_NONE; };
 
-	/* virtual */ const char *GetName() { return "null"; }
-	/* virtual */ int GetBytesPerPixel() { return 0; }
+	const char *GetName() override { return "null"; }
+	int GetBytesPerPixel() override { return 0; }
 };
 
 /** Factory for the blitter that does nothing. */
 class FBlitter_Null : public BlitterFactory {
 public:
 	FBlitter_Null() : BlitterFactory("null", "Null Blitter (does nothing)") {}
-	/* virtual */ Blitter *CreateInstance() { return new Blitter_Null(); }
+	Blitter *CreateInstance() override { return new Blitter_Null(); }
 };
 
 #endif /* BLITTER_NULL_HPP */