diff --git a/src/Resources.cpp b/src/Resources.cpp
index 29e0976..f820938 100644
--- a/src/Resources.cpp
+++ b/src/Resources.cpp
@@ -6,12 +6,6 @@
 
 #include <allegro5/allegro.h>
 
-Resources::Resources()
-{
-    for (const auto& [resourceType, path] : resourcePaths_)
-        bitmaps_[resourceType] = ::al_load_bitmap(path.c_str());
-}
-
 Resources::~Resources()
 {
     for (const auto& [_, bitmap] : bitmaps_)
@@ -20,6 +14,9 @@ Resources::~Resources()
 
 ALLEGRO_BITMAP* Resources::getBitmap(ResourceType resourceType) const
 {
+    if (bitmaps_.empty())
+        for (const auto& [resType, path] : resourcePaths_)
+            bitmaps_[resType] = ::al_load_bitmap(path.c_str());
     return bitmaps_.at(resourceType);
 }
 
diff --git a/src/Resources.h b/src/Resources.h
index 61862fc..4f8ecf5 100644
--- a/src/Resources.h
+++ b/src/Resources.h
@@ -11,14 +11,14 @@ struct ALLEGRO_BITMAP;
 class Resources
 {
 public:
-    Resources();
+    Resources() = default;
     ~Resources();
 
     Resources& operator=(const Resources& other) = delete;
     Resources(const Resources& other) = delete;
 
-    Resources& operator=(Resources&& other) = default;
-    Resources(Resources&& other) = default;
+    Resources& operator=(Resources&& other) = delete;
+    Resources(Resources&& other) = delete;
 
     ALLEGRO_BITMAP* getBitmap(ResourceType resourceType) const;
 
@@ -50,5 +50,5 @@ class Resources
         {ResourceType::ENEMY_TANK_TIER_3, "image/board/tank_tier3_enemy.tga"},
         {ResourceType::ENEMY_TANK_TIER_4, "image/board/tank_tier4_enemy.tga"}};
 
-    std::unordered_map<ResourceType, ALLEGRO_BITMAP*> bitmaps_;
+    mutable std::unordered_map<ResourceType, ALLEGRO_BITMAP*> bitmaps_;
 };
diff --git a/src/Screen.cpp b/src/Screen.cpp
index 3d9d81b..8834807 100644
--- a/src/Screen.cpp
+++ b/src/Screen.cpp
@@ -37,7 +37,6 @@ bool Screen::init()
 
     ::al_set_window_title(::al_get_current_display(), "TankBle");
 
-    resources_ = {};
     font_ = ::al_create_builtin_font();
 
     return true;