diff --git a/init.lua b/init.lua
index 970744a..0ff846a 100644
--- a/init.lua
+++ b/init.lua
@@ -122,6 +122,7 @@ for _,tube in ipairs(nixie_types) do
 		},
 		use_texture_alpha = "clip",
 		groups = groups,
+		is_ground_content = false,
 		paramtype = "light",
 		paramtype2 = "facedir",
 		light_source = light,
@@ -157,6 +158,7 @@ for _,tube in ipairs(nixie_types) do
 		},
 		use_texture_alpha = "clip",
 		groups = groups,
+		is_ground_content = false,
 		paramtype = "light",
 		paramtype2 = "facedir",
 		light_source = light,
@@ -194,6 +196,7 @@ for _,tube in ipairs(nixie_types) do
 			},
 			use_texture_alpha = "clip",
 			groups = groups,
+			is_ground_content = false,
 			paramtype = "light",
 			paramtype2 = "facedir",
 			light_source = light2,
@@ -466,6 +469,7 @@ for i in ipairs(alnum_chars) do
 		},
 		use_texture_alpha = "clip",
 		groups = groups,
+		is_ground_content = false,
 		paramtype = "light",
 		paramtype2 = "facedir",
 		light_source = light,