diff --git a/nix/pkgs/sheepshaver.nix b/nix/pkgs/sheepshaver.nix
index 23d88dbac0..cee98df71c 100644
--- a/nix/pkgs/sheepshaver.nix
+++ b/nix/pkgs/sheepshaver.nix
@@ -31,6 +31,7 @@ pkgs.stdenv.mkDerivation rec {
   configureFlags = [
     "--enable-sdl-audio"
   ];
+  CPPFLAGS = "-DSTDC_HEADERS";
 
   preConfigure = ''
     NO_CONFIGURE=1 ./autogen.sh