diff --git a/direct/src/directd/Sources.pp b/direct/src/directd/Sources.pp
index 6f14c8195a..32c721612e 100644
--- a/direct/src/directd/Sources.pp
+++ b/direct/src/directd/Sources.pp
@@ -1,4 +1,7 @@
 
+// This package presently only builds on Windows.
+#define DIRECTORY_IF_WINDOWS yes
+
 //#define LOCAL_LIBS \
 //    directbase
 #define OTHER_LIBS \