diff --git a/src/VisibleObjects/Ball.h b/src/VisibleObjects/Ball.h
index 09a9d59..992630b 100644
--- a/src/VisibleObjects/Ball.h
+++ b/src/VisibleObjects/Ball.h
@@ -22,14 +22,9 @@ private:
 
 public:
     explicit Ball(const SDL_Point *screen, const PlayerPaddle *leftPaddle, const PlayerPaddle *rightPaddle,
-                  Score *score) {
-        this->score = score;
-        this->screen = screen;
-        this->leftPaddle = leftPaddle;
-        this->rightPaddle = rightPaddle;
-        this->x = screen->x / 2;
-        this->y = screen->y / 2;
-        vec2d = new Vec2d(6);
+                  Score *score) :
+            score(score), screen(screen), leftPaddle(leftPaddle), rightPaddle(rightPaddle), x(screen->x / 2),
+            y(screen->y / 2), vec2d(new Vec2d(6)) {
     }
 
     void resetPosition() {
@@ -66,11 +61,11 @@ public:
     }
 
 private:
-    bool collidedScreenEdgeVertical() {
+    [[nodiscard]]bool collidedScreenEdgeVertical() const {
         return y - RADIUS <= 0 || y + RADIUS >= screen->y;
     }
 
-    std::optional<Side> collidedScreenEdgeHorizontal() {
+    [[nodiscard]] std::optional<Side> collidedScreenEdgeHorizontal() const {
         if (x + RADIUS >= screen->x)
             return Side::RIGHT;
         else if (x - RADIUS <= 0)
@@ -78,7 +73,7 @@ private:
         return std::nullopt;
     }
 
-    std::optional<Side> collidedPaddle() {
+    [[nodiscard]] std::optional<Side> collidedPaddle() const {
         // Right paddle
         if (x + RADIUS >= rightPaddle->x &&
             y >= rightPaddle->y &&
diff --git a/src/VisibleObjects/PlayerPaddle.h b/src/VisibleObjects/PlayerPaddle.h
index 2810235..3bf8f67 100644
--- a/src/VisibleObjects/PlayerPaddle.h
+++ b/src/VisibleObjects/PlayerPaddle.h
@@ -44,13 +44,13 @@ public:
         SDL_RenderFillRect(renderer, this);
     }
 
-    void startMoving(bool up) {
+    void startMoving(const bool up) {
         if (up)
             movingUp = true;
         else movingDown = true;
     }
 
-    void stopMoving(bool up) {
+    void stopMoving(const bool up) {
         if (up)
             movingUp = false;
         else movingDown = false;
@@ -68,11 +68,11 @@ public:
     }
 
 private:
-    bool canMoveDown() {
+    [[nodiscard]] bool canMoveDown() const {
         return y + h < screen->y;
     }
 
-    bool canMoveUp() {
+    [[nodiscard]] bool canMoveUp() const {
         return y > 0;
     }
 
diff --git a/src/VisibleObjects/Score.h b/src/VisibleObjects/Score.h
index 3760d99..2d9d1fc 100644
--- a/src/VisibleObjects/Score.h
+++ b/src/VisibleObjects/Score.h
@@ -36,7 +36,7 @@ private:
     const int shadowOffset = 3;
 
 public:
-    explicit Score(uint8_t max_score, SDL_Point *screenSize, const std::function<void(Side)> whenWon) : MAX_SCORE(
+    explicit Score(uint8_t max_score, SDL_Point *screenSize, const std::function<void(Side)> &whenWon) : MAX_SCORE(
             max_score), whenWon(whenWon) {
         resetScore();
         if (defaultFontPath == nullptr) {
@@ -57,17 +57,14 @@ public:
     ~Score() {
         if (font)
             TTF_CloseFont(font);
-        if (surface)
-            SDL_FreeSurface(surface);
+        SDL_FreeSurface(surface);
     }
 
     void update() {
         if (!hasIncremented && surface != nullptr && shadowSurface != nullptr) return;
 
-        if (surface != nullptr)
-            SDL_FreeSurface(surface);
-        if (shadowSurface != nullptr)
-            SDL_FreeSurface(shadowSurface);
+        SDL_FreeSurface(surface);
+        SDL_FreeSurface(shadowSurface);
 
         hasIncremented = false;
         char score_text[8];
@@ -112,7 +109,7 @@ public:
         leftScore = rightScore = 0;
     }
 
-    void incrementScore(Side side) {
+    void incrementScore(const Side side) {
         hasIncremented = true;
         uint8_t temp;
         switch (side) {