diff --git a/turtles/mine.lua b/turtles/mine.lua
index 639b690..992537d 100644
--- a/turtles/mine.lua
+++ b/turtles/mine.lua
@@ -165,14 +165,25 @@ end
 
 -- Find the next unmined shaft and end up in front of it
 function find_next_shaft()
+    function is_shaft_pos()
+        if side % 2 == 1 then
+            return false
+        elseif side % 4 == 0 then
+            return height % 3 == 0
+        elseif side % 4 == 2 then
+            return height % 3 ~= 0
+        end
+    end
+    function is_shaft()
+        return is_shaft_pos() and turtle.detect()
+    end
+
     go_to(0, 0, 0)
 
     while true do
         for hei=1,MAX_HEIGHT-1 do
-            if (height % 3) == 0 then
-                if turtle.detect() then
-                    return
-                end
+            if is_shaft() then
+                return
             end
 
             if turtle.detectUp() then
@@ -180,24 +191,20 @@ function find_next_shaft()
             end
             move_up()
         end
-        if turtle.detect() then
+        if is_shaft() then
             return
         end
 
         turn_abs(1)
-        for i=0,1 do
-            if turtle.detect() then
-                turtle.dig()
-            end
-            move_forward()
+        if turtle.detect() then
+            turtle.dig()
         end
+        move_forward()
         turn_abs(0)
 
         for hei=MAX_HEIGHT-1,1,-1 do
-            if (height % 3) ~= 0 then
-                if turtle.detect() then
-                    return
-                end
+            if is_shaft() then
+                return
             end
 
             if turtle.detectDown() then
@@ -205,14 +212,15 @@ function find_next_shaft()
             end
             move_down()
         end
+        if is_shaft() then
+            return
+        end
 
         turn_abs(1)
-        for i=0,1 do
-            if turtle.detect() then
-                turtle.dig()
-            end
-            move_forward()
+        if turtle.detect() then
+            turtle.dig()
         end
+        move_forward()
         turn_abs(0)
     end
 end