diff --git a/dtool/Config.pp b/dtool/Config.pp
index a1644b5c25..9ad538b6aa 100644
--- a/dtool/Config.pp
+++ b/dtool/Config.pp
@@ -254,6 +254,12 @@
 // Should we try to build the SGI-specific glxdisplay?
 #define HAVE_SGIGL $[eq $[PLATFORM],Irix]
 
+// Is DirectX available, and should we try to build with it?
+#define DX_IPATH
+#define DX_LPATH
+#define DX_LIBS
+#define HAVE_DX
+
 // Do you want to build the Renderman interface?
 #define HAVE_RIB