diff --git a/src/spritecache.cpp b/src/spritecache.cpp
index 91eae15970..bf1086e5ef 100644
--- a/src/spritecache.cpp
+++ b/src/spritecache.cpp
@@ -565,7 +565,7 @@ void ReadGRFSpriteOffsets(byte container_version)
  * @param container_version Container version of the GRF.
  * @return True if a valid sprite was loaded, false on any error.
  */
-bool LoadNextSprite(int load_index, byte file_slot, uint file_sprite_id, byte container_version)
+bool LoadNextSprite(int load_index, uint file_slot, uint file_sprite_id, byte container_version)
 {
 	size_t file_pos = FioGetPos();
 
diff --git a/src/spritecache.h b/src/spritecache.h
index 5e156efdfb..bf2f85ff54 100644
--- a/src/spritecache.h
+++ b/src/spritecache.h
@@ -54,7 +54,7 @@ void IncreaseSpriteLRU();
 
 void ReadGRFSpriteOffsets(byte container_version);
 size_t GetGRFSpriteOffset(uint32 id);
-bool LoadNextSprite(int load_index, byte file_index, uint file_sprite_id, byte container_version);
+bool LoadNextSprite(int load_index, uint file_index, uint file_sprite_id, byte container_version);
 bool SkipSpriteData(byte type, uint16 num);
 void DupSprite(SpriteID old_spr, SpriteID new_spr);