diff --git a/xpcom/build/nsXPCOMPrivate.h b/xpcom/build/nsXPCOMPrivate.h
index 2f773de02b6..309a16f5219 100644
--- a/xpcom/build/nsXPCOMPrivate.h
+++ b/xpcom/build/nsXPCOMPrivate.h
@@ -150,6 +150,7 @@ NS_GetFrozenFunctions(XPCOMFunctions *entryPoints, const char* libraryPath);
 
 #define GRE_CONF_NAME ".gre.config"
 #define GRE_CONF_PATH "/etc/gre.conf"
+#define GRE_CONF_DIR  "/etc/gre.d/"
 #endif