diff --git a/init.lua b/init.lua
index 0cd8ea8..42a58a8 100644
--- a/init.lua
+++ b/init.lua
@@ -88,6 +88,7 @@ do
 		tiles = { { name = "tsm_surprise_question_anim.png", animation = {
 			type = "vertical_frames", aspect_w=16, aspect_h=16, length=3.0 } } },
 		drop = "",
+		is_ground_content = false,
 		groups = { dig_immediate=2, },
 		sounds = {
 			place = { name = "tsm_surprise_question_dig", gain = 1 },