diff --git a/data/mods/experimental/init.lua b/data/mods/experimental/init.lua
index c37488d04..5f01d8b78 100644
--- a/data/mods/experimental/init.lua
+++ b/data/mods/experimental/init.lua
@@ -330,7 +330,7 @@ function TNT:on_activate(staticdata)
 	self.object:setvelocity({x=0, y=4, z=0})
 	self.object:setacceleration({x=0, y=-10, z=0})
 	self.object:settexturemod("^[brighten")
-	self.object:set_armor_groups({foo=1,bar=2})
+	self.object:set_armor_groups({immortal=1})
 end
 
 -- Called periodically