diff --git a/init.lua b/init.lua
index 3d02216..e4e9c8e 100644
--- a/init.lua
+++ b/init.lua
@@ -23,12 +23,28 @@ AuthInitFile( world_path, "auth.db" )
 local auth_filter = AuthFilter( world_path, "greenlist.mt" )
 local auth_db = AuthDatabase( world_path, "auth.db" )
 local auth_watchdog = AuthWatchdog( )
+local is_50 = minetest.has_feature("object_use_texture_alpha")
+local is_54 = minetest.has_feature("object_use_texture_alpha")
 
-if minetest.register_on_auth_fail then
-	minetest.register_on_auth_fail( function ( player_name, player_ip )
-		auth_db.on_login_failure( player_name, player_ip )
-		auth_watchdog.on_failure( convert_ipv4( player_ip ) )
-	end )
+if is_50 then
+	if minetest.register_on_auth_fail then
+		minetest.register_on_auth_fail( function ( player_name, player_ip )
+			auth_db.on_login_failure( player_name, player_ip )
+			auth_watchdog.on_failure( convert_ipv4( player_ip ) )
+		end )
+	end
+end
+
+if is_54 then
+	if minetest.register_on_authplayer then
+		minetest.register_on_authplayer( function ( player_name, player_ip, is_success )
+			if is_success then
+				return
+			end
+			auth_db.on_login_failure( player_name, player_ip )
+			auth_watchdog.on_failure( convert_ipv4( player_ip ) )
+		end )
+	end
 end
 
 minetest.register_on_prejoinplayer( function ( player_name, player_ip )