diff --git a/mods/doors/init.lua b/mods/doors/init.lua
index 2b326b07..902e1cf5 100644
--- a/mods/doors/init.lua
+++ b/mods/doors/init.lua
@@ -26,6 +26,7 @@ function doors.register_door(name, def)
 		def.sound_open_door = "doors_door_open"
 	end
 	if def.only_placer_can_open then
+		-- unaffected by explosions
 		def.on_blast = function() end
 	end
 	
diff --git a/mods/fire/init.lua b/mods/fire/init.lua
index c07ad35f..89488726 100644
--- a/mods/fire/init.lua
+++ b/mods/fire/init.lua
@@ -25,6 +25,7 @@ minetest.register_node("fire:basic_flame", {
 		minetest.after(0, fire.on_flame_remove_at, pos)
 	end,
 
+	-- unaffected by explosions
 	on_blast = function() end,
 })
 
diff --git a/mods/tnt/init.lua b/mods/tnt/init.lua
index 94925b75..c7785002 100644
--- a/mods/tnt/init.lua
+++ b/mods/tnt/init.lua
@@ -248,6 +248,7 @@ minetest.register_node("tnt:tnt_burning", {
 	drop = "",
 	sounds = default.node_sound_wood_defaults(),
 	on_timer = boom,
+	-- unaffected by explosions
 	on_blast = function() end,
 })
 
@@ -261,6 +262,7 @@ minetest.register_node("tnt:boom", {
 	on_timer = function(pos, elapsed)
 		minetest.remove_node(pos)
 	end,
+	-- unaffected by explosions
 	on_blast = function() end,
 })
 
@@ -328,6 +330,7 @@ minetest.register_node("tnt:gunpowder_burning", {
 		end
 		minetest.remove_node(pos)
 	end,
+	-- unaffected by explosions
 	on_blast = function() end,
 })