diff --git a/gpu.lua b/gpu.lua
index 4f5b37f..1acad1d 100644
--- a/gpu.lua
+++ b/gpu.lua
@@ -935,7 +935,7 @@ end
 
 minetest.register_node("digistuff:gpu", {
 	description = "Digilines 2D Graphics Processor",
-	groups = { cracky = 3 },
+	groups = { cracky = 3, heatsinkable = 1 },
 	is_ground_content = false,
 	on_construct = function(pos)
 		local meta = minetest.get_meta(pos)
diff --git a/ioexpander.lua b/ioexpander.lua
index 3f4a4cc..ab505a2 100644
--- a/ioexpander.lua
+++ b/ioexpander.lua
@@ -107,7 +107,7 @@ for i=0,15,1 do
 	local offstate = i == 0
 	minetest.register_node("digistuff:ioexpander_"..i, {
 		description = offstate and "Digilines I/O Expander" or string.format("Digilines I/O Expander (on state %X - you hacker you!)",i),
-		groups = offstate and {cracky = 3,} or {cracky = 3,not_in_creative_inventory = 1,},
+		groups = {cracky = 3,heatsinkable=1,not_in_creative_inventory = (not offstate) and 1,},
 		is_ground_content = false,
 		on_construct = function(pos)
 			local meta = minetest.get_meta(pos)
diff --git a/memory.lua b/memory.lua
index 33e8503..20f85f7 100644
--- a/memory.lua
+++ b/memory.lua
@@ -1,6 +1,6 @@
 minetest.register_node("digistuff:ram", {
 	description = "Digilines 128Kbit SRAM",
-	groups = {cracky=3},
+	groups = {cracky=3, heatsinkable=1},
 	is_ground_content = false,
 	on_construct = function(pos)
 		local meta = minetest.get_meta(pos)
@@ -64,7 +64,7 @@ minetest.register_node("digistuff:ram", {
 
 minetest.register_node("digistuff:eeprom", {
 	description = "Digilines 128Kbit EEPROM",
-	groups = {cracky=3},
+	groups = {cracky=3, heatsinkable=1},
 	is_ground_content = false,
 	on_construct = function(pos)
 		local meta = minetest.get_meta(pos)
diff --git a/nic.lua b/nic.lua
index 8c4b415..46b5989 100644
--- a/nic.lua
+++ b/nic.lua
@@ -1,7 +1,7 @@
 local http = ...
 minetest.register_node("digistuff:nic", {
 	description = "Digilines NIC",
-	groups = {cracky=3},
+	groups = {cracky=3, heatsinkable=1},
 	is_ground_content = false,
 	on_construct = function(pos)
 		local meta = minetest.get_meta(pos)
diff --git a/sillystuff.lua b/sillystuff.lua
index 33a6b6e..25aa07c 100644
--- a/sillystuff.lua
+++ b/sillystuff.lua
@@ -1,18 +1,32 @@
-local heatsinkable_nodes = {
-	["digistuff:nic"] = true,
-	["digistuff:gpu"] = true,
-	["digistuff:ram"] = true,
-	["digistuff:eeprom"] = true,
-}
 
 for i = 0, 15, 1 do
 	local bit0 = i % 2 > 0 and "1" or "0"
 	local bit1 = i % 4 > 1 and "1" or "0"
 	local bit2 = i % 8 > 3 and "1" or "0"
 	local bit3 = i % 16 > 7 and "1" or "0"
-	heatsinkable_nodes["mesecons_luacontroller:luacontroller" .. bit0 .. bit1 .. bit2 .. bit3] = true
-	heatsinkable_nodes["mooncontroller:mooncontroller" .. bit0 .. bit1 .. bit2 .. bit3] = true
-	heatsinkable_nodes["digistuff:ioexpander_" .. i] = true
+	local bits = bit0 .. bit1 .. bit2 .. bit3
+	do
+		local name = "mesecons_luacontroller:luacontroller" .. bits
+		local def = core.registered_nodes[name]
+		if def then
+			local groups = table.copy(def.groups)
+			groups.heatsinkable = 1
+			core.override_item(name, {
+				groups = groups
+			})
+		end
+	end
+	do
+		local name = "mooncontroller:mooncontroller" .. bits
+		local def = core.registered_nodes[name]
+		if def then
+			local groups = table.copy(def.groups)
+			groups.heatsinkable = 1
+			core.override_item(name, {
+				groups = groups
+			})
+		end
+	end
 end
 
 minetest.register_node("digistuff:heatsink", {
@@ -46,7 +60,7 @@ minetest.register_node("digistuff:heatsink", {
 	},
 	after_place_node = function(pos)
 		local icpos = vector.add(pos,vector.new(0,-1,0))
-		if heatsinkable_nodes[minetest.get_node(icpos).name] then
+		if core.get_item_group(core.get_node(icpos).name, "heatsinkable") then
 			minetest.set_node(pos,{name = "digistuff:heatsink_onic"})
 		end
 	end,