diff --git a/pkgs/development/libraries/SDL_gfx/default.nix b/pkgs/development/libraries/SDL_gfx/default.nix
index a8227e608964..41d84184c165 100644
--- a/pkgs/development/libraries/SDL_gfx/default.nix
+++ b/pkgs/development/libraries/SDL_gfx/default.nix
@@ -9,6 +9,7 @@ stdenv.mkDerivation rec {
     sha256 = "0ijljhs0v99dj6y27hc10z6qchyp8gdp4199y6jzngy6dzxlzsvw";
   };
 
+  # SDL_gfx.pc refers to sdl.pc and some SDL_gfx headers import SDL.h
   propagatedBuildInputs = [ SDL ];
   buildInputs = [ SDL ] ;