diff --git a/Makefile b/Makefile
index db750a45..d4825b37 100644
--- a/Makefile
+++ b/Makefile
@@ -194,6 +194,7 @@ CCOPTS_SHARED += -DDUK_OPT_DEBUG_BUFSIZE=512
 #CCOPTS_SHARED += -DDUK_OPT_NO_ES6_OBJECT_SETPROTOTYPEOF
 #CCOPTS_SHARED += -DDUK_OPT_NO_ES6_PROXY
 #CCOPTS_SHARED += -DDUK_OPT_NO_ZERO_BUFFER_DATA
+#CCOPTS_SHARED += -DDUK_OPT_USER_INITJS='"this.foo = 123"'
 #CCOPTS_SHARED += -DDUK_CMDLINE_BAREBONES
 CCOPTS_NONDEBUG = $(CCOPTS_SHARED) -Os -fomit-frame-pointer
 CCOPTS_NONDEBUG += -g -ggdb