diff --git a/kai/lib.lua b/kai/lib.lua
index 7d8b45e..602567a 100644
--- a/kai/lib.lua
+++ b/kai/lib.lua
@@ -21,6 +21,10 @@ state = (function ()
     })
 end)()
 
+if state.x == nil or state.y == nil or state.z == nil or state.o == nil then
+    print("[WARNING] position is not set")
+end
+
 --[[
     orientation:
     0 = South (+z)
@@ -45,7 +49,7 @@ return {
     fwd = move(turtle.forward, function()
         if state.o == 1 or state.o == 3 then
             state.x = state.x + ((state.o == 1) and -1 or 1)
-        else
+        elseif state.o == 0 or state.o == 2 then
             state.z = state.z + ((state.o == 2) and -1 or 1)
         end
     end),
@@ -53,7 +57,7 @@ return {
     back = move(turtle.back, function()
         if state.o == 1 or state.o == 3 then
             state.x = state.x + ((state.o == 1 and 1 or -1))
-        else
+        elseif state.o == 0 or state.o == 2 then
             state.z = state.z + ((state.o == 2) and 1 or -1)
         end
     end),