diff --git a/direct/src/plugin/p3dSession.cxx b/direct/src/plugin/p3dSession.cxx
index b7b979721d..2b10ff53e8 100644
--- a/direct/src/plugin/p3dSession.cxx
+++ b/direct/src/plugin/p3dSession.cxx
@@ -761,6 +761,9 @@ start_p3dpython(P3DInstance *inst) {
     "TMP", "TEMP", "HOME", "USER", 
 #ifdef _WIN32
     "SYSTEMROOT", "USERPROFILE", "COMSPEC", "PANDA_ROOT",
+#endif
+#ifdef HAVE_X11
+    "DISPLAY",
 #endif
     NULL
   };