diff --git a/src/drawing/drawing.h b/src/drawing/drawing.h
index 05125a9a38..45baa09cdf 100644
--- a/src/drawing/drawing.h
+++ b/src/drawing/drawing.h
@@ -109,7 +109,7 @@ int gfx_load_g1();
 int gfx_load_g2();
 void sub_68371D();
 void gfx_bmp_sprite_to_buffer(uint8* palette_pointer, uint8* unknown_pointer, uint8* source_pointer, uint8* dest_pointer, rct_g1_element* source_image, rct_drawpixelinfo *dest_dpi, int height, int width, int image_type);
-void gfx_rle_sprite_to_buffer(uint8* source_bits_pointer, uint8* dest_bits_pointer, uint8* palette_pointer, rct_drawpixelinfo *dpi, int image_type, int source_y_start, int height, int source_x_start, int width);
+void gfx_rle_sprite_to_buffer(const uint8* source_bits_pointer, uint8* dest_bits_pointer, const uint8* palette_pointer, const rct_drawpixelinfo *dpi, int image_type, int source_y_start, int height, int source_x_start, int width);
 void gfx_draw_sprite(rct_drawpixelinfo *dpi, int image_id, int x, int y, uint32 tertiary_colour);
 void gfx_draw_sprite_palette_set(rct_drawpixelinfo *dpi, int image_id, int x, int y, uint8* palette_pointer, uint8* unknown_pointer);
 void gfx_draw_sprite_raw_masked(rct_drawpixelinfo *dpi, int x, int y, int maskImage, int colourImage);
diff --git a/src/drawing/sprite.c b/src/drawing/sprite.c
index d269e7d1c6..918321f0a5 100644
--- a/src/drawing/sprite.c
+++ b/src/drawing/sprite.c
@@ -258,11 +258,10 @@ void gfx_bmp_sprite_to_buffer(uint8* palette_pointer, uint8* unknown_pointer, ui
  * This function copies the sprite data onto the screen
  *  rct2: 0x0067AA18
  */
-void gfx_rle_sprite_to_buffer(uint8* source_bits_pointer, uint8* dest_bits_pointer, uint8* palette_pointer, rct_drawpixelinfo *dpi, int image_type, int source_y_start, int height, int source_x_start, int width){
+void gfx_rle_sprite_to_buffer(const uint8* source_bits_pointer, uint8* dest_bits_pointer, const uint8* palette_pointer, const rct_drawpixelinfo *dpi, int image_type, int source_y_start, int height, int source_x_start, int width){
 	int zoom_level = dpi->zoom_level;
 	int zoom_amount = 1 << zoom_level;
 	int zoom_mask = 0xFFFFFFFF << zoom_level;
-	uint8* next_source_pointer;
 	uint8* next_dest_pointer = dest_bits_pointer;
 
 	int line_width = (dpi->width >> zoom_level) + dpi->pitch;
@@ -278,13 +277,13 @@ void gfx_rle_sprite_to_buffer(uint8* source_bits_pointer, uint8* dest_bits_point
 
 		//The first part of the source pointer is a list of offsets to different lines
 		//This will move the pointer to the correct source line.
-		next_source_pointer = source_bits_pointer + ((uint16*)source_bits_pointer)[y];
+		const uint8 *next_source_pointer = source_bits_pointer + ((uint16*)source_bits_pointer)[y];
 
 		uint8 last_data_line = 0;
 
 		//For every data section in the line
 		while (!last_data_line){
-			uint8* source_pointer = next_source_pointer;
+			const uint8* source_pointer = next_source_pointer;
 			uint8* dest_pointer = next_dest_pointer;
 
 			int no_pixels = *source_pointer++;