diff --git a/letter_cutter.lua b/letter_cutter.lua
index 4c82be6..ea3a82d 100644
--- a/letter_cutter.lua
+++ b/letter_cutter.lua
@@ -346,6 +346,7 @@ minetest.register_node("letters:letter_cutter_lower",  {
 	sunlight_propagates = true,
 	paramtype2 = "facedir",
 	groups = {choppy = 2,oddly_breakable_by_hand = 2},
+	is_ground_content = false,
 	sounds = default.node_sound_wood_defaults(),
 	on_construct = letter_cutter.on_construct,
 	can_dig = letter_cutter.can_dig,
@@ -400,6 +401,7 @@ minetest.register_node("letters:letter_cutter_upper",  {
 	sunlight_propagates = true,
 	paramtype2 = "facedir",
 	groups = {choppy = 2,oddly_breakable_by_hand = 2},
+	is_ground_content = false,
 	sounds = default.node_sound_wood_defaults(),
 	on_construct = letter_cutter.on_construct,
 	can_dig = letter_cutter.can_dig,
@@ -456,6 +458,7 @@ minetest.register_node("letters:letter_cutter_digit",  {
 	sunlight_propagates = true,
 	paramtype2 = "facedir",
 	groups = {choppy = 2,oddly_breakable_by_hand = 2},
+	is_ground_content = false,
 	sounds = default.node_sound_wood_defaults(),
 	on_construct = letter_cutter.on_construct,
 	can_dig = letter_cutter.can_dig,