diff --git a/ferns/treefern.lua b/ferns/treefern.lua
index d95bfb8..dc6d2e7 100644
--- a/ferns/treefern.lua
+++ b/ferns/treefern.lua
@@ -11,6 +11,8 @@ local S = minetest.get_translator("ferns")
 
 assert(abstract_ferns.config.enable_treefern == true)
 
+local random = math.random
+
 abstract_ferns.grow_tree_fern = function(pos)
 
 	local pos_aux = {x = pos.x, y = pos.y + 1, z = pos.z}
@@ -20,12 +22,12 @@ abstract_ferns.grow_tree_fern = function(pos)
 		return
 	end
 
-	local size = math.random(1, 4) + math.random(1, 4)
+	local size = random(1, 4) + random(1, 4)
 	if (size > 5) then
 		size = 10 - size
 	end
 	size = size + 1
-	local crown = ({ "ferns:tree_fern_leaves", "ferns:tree_fern_leaves_02" })[math.random(1, 2)]
+	local crown = ({ "ferns:tree_fern_leaves", "ferns:tree_fern_leaves_02" })[random(1, 2)]
 
 	local i = 1
 	local brk = false