diff --git a/js/Player.js b/js/Player.js
index c8f184f..5601fae 100644
--- a/js/Player.js
+++ b/js/Player.js
@@ -39,12 +39,12 @@ export class Player extends Movable {
          }
          break
       case 'up':
-         if (this.y > Game.row(0)) {
+         if (Game.withinTopBoundary(this.y)) {
             this.move(0, -Game.CELL_HEIGHT)
          }
          break
       case 'down':
-         if (this.y < Game.row(5)) {
+         if (Game.withinBottomBoundary(this.y)) {
             this.move(0, Game.CELL_HEIGHT)
          }
          break
diff --git a/js/constants/game.js b/js/constants/game.js
index 6bbee50..31c8e0d 100644
--- a/js/constants/game.js
+++ b/js/constants/game.js
@@ -24,5 +24,13 @@ export class Game {
    static withinRightBoundary(x) {
       return x < Game.col(Game.HORIZON_CELLS)
    }
+
+   static withinTopBoundary(y) {
+      return y > Game.TOP_BOUNDARY
+   }
+
+   static withinBottomBoundary(y) {
+      return y < Game.row(5)
+   }
 }