diff --git a/spec/command_spec.cr b/spec/command_spec.cr
index 82b2004..5937af4 100644
--- a/spec/command_spec.cr
+++ b/spec/command_spec.cr
@@ -16,7 +16,7 @@ describe Game::Command do
     tile.should be_a(Game::BuildingTile)
   end
 
-  it "should restrict build if not enought resources" do
+  it "should restrict building if not enought resources" do
     world = Game::World.new create_map_2x2
     point = Game::Point.new 1, 0
     building = Game::Building.new Game::Building::Type::StartPoint, **{
@@ -24,8 +24,7 @@ describe Game::Command do
         ts: 10,
         cost: Game::Resources.new({
           Game::Resources::Type::Crystals => 100,
-        }),
-        requirements: [] of Game::Building::Type
+        })
       ),
     }
     command = Game::BuildCommand.new point, building
diff --git a/src/game/building.cr b/src/game/building.cr
index 7d8fb10..75dd3a0 100644
--- a/src/game/building.cr
+++ b/src/game/building.cr
@@ -9,17 +9,19 @@ module Game
   end
 
   class Mining
-    def initialize(@ts : TimeSpan, @input : Resources, @res : Resources::Type, @cap : Capacity)
+    def initialize(@ts : TimeSpan, @dep : DepositSpan)
     end
 
     getter ts
-    getter input
-    getter res
-    getter cap
+    getter dep
   end
 
   class Construction
-    def initialize(@ts : TimeSpan, @cost : Resources, @requirements : Array(Building::Type))
+    def initialize(
+      @ts : TimeSpan,
+      @cost : Resources,
+      @requirements : Array(Building::Type) = [] of Building::Type
+    )
     end
 
     getter ts
@@ -27,11 +29,11 @@ module Game
     getter requirements
 
     def self.immediatly
-      Construction.new 0, Resources.new, [] of Building::Type
+      Construction.new 0, Resources.new
     end
 
     def self.free(ts : TimeSpan)
-      Construction.new ts, Resources.new, [] of Building::Type
+      Construction.new ts, Resources.new
     end
   end