diff --git a/panda/src/rocket/Sources.pp b/panda/src/rocket/Sources.pp
index b493b52298..2d90ee0e89 100644
--- a/panda/src/rocket/Sources.pp
+++ b/panda/src/rocket/Sources.pp
@@ -2,6 +2,7 @@
                    p3dtoolutil:c p3dtoolbase:c p3dtool:m p3prc:c
 
 #define USE_PACKAGES rocket
+#define BUILD_DIRECTORY $[HAVE_ROCKET]
 
 #define BUILDING_DLL BUILDING_ROCKET