diff --git a/init.lua b/init.lua
index a92eed7..62bbbf0 100644
--- a/init.lua
+++ b/init.lua
@@ -57,7 +57,9 @@ local stairsplus_patterns = {
 
 
 local function register_stairsplus_alias_force(modname, origname, newmod, newname)
-	for prefix, suffix in pairs(stairsplus_patterns) do
+	for _, pattern in ipairs(stairsplus_patterns) do
+		local prefix = pattern[1]
+		local suffix = pattern[2]
 		minetest.register_alias_force(
 				modname .. ":" .. prefix ..
 				origname .. suffix,