diff --git a/src/Draw.cpp b/src/Draw.cpp
index 6b1ea686..bd7ed4b0 100644
--- a/src/Draw.cpp
+++ b/src/Draw.cpp
@@ -291,7 +291,7 @@ static bool LoadBitmap(SDL_RWops *fp, Surface_Ids surf_no, bool create_surface)
 								}
 
 								for (int i = 1; i < magnification; ++i)
-									memcpy(dst_row + i * surf[surf_no].surface->pitch, dst_row, surf[surf_no].surface->w * sizeof(unsigned long));
+									memcpy(dst_row + i * surf[surf_no].surface->pitch, dst_row, surf[surf_no].surface->w * 4);
 							}
 
 							SDL_FreeSurface(converted_surface);