diff --git a/init.lua b/init.lua
index 663b6c7..72f48d0 100644
--- a/init.lua
+++ b/init.lua
@@ -46,15 +46,31 @@ end)
 minetest.register_chatcommand("strength", {
     description = "set max rumble strength (between 0 and 1)",
     func = function(text)
-        rumble_strength_max = (text)
-        minetest.display_chat_message("max rumble strength set to "..rumble_strength_max)
+        if (string.match((text), "^%d+$")) then
+            rumble_strength_max = (text)
+            minetest.display_chat_message("max rumble strength set to "..rumble_strength_max)
+        else
+            minetest.display_chat_message(minetest.colorize("#FF0", "error: value after .strength should be a positive number"))
+        end
     end,
 })
 
 minetest.register_chatcommand("duration", {
     description = "set max rumble duration (in seconds)",
     func = function(text)
-        rumble_duration_max = (text)
-        minetest.display_chat_message("max rumble duration set to "..rumble_duration_max)
+        if (string.match((text), "^%d+$")) then
+            rumble_duration_max = (text)
+            minetest.display_chat_message("max rumble duration set to "..rumble_duration_max)
+        else
+            minetest.display_chat_message(minetest.colorize("#FF0", "error: value after .duration should be a positive number"))
+        end
+    end,
+})
+
+minetest.register_chatcommand("settings", {
+    description = "shows current values of settings",
+    func = function()
+        minetest.display_chat_message("max rumble strength: "..rumble_strength_max)
+        minetest.display_chat_message("max rumble duration: "..rumble_duration_max)
     end,
 })