diff --git a/src/client/graphics/layers/UnitLayer.ts b/src/client/graphics/layers/UnitLayer.ts
index 5cae90c36..3e59dc7ba 100644
--- a/src/client/graphics/layers/UnitLayer.ts
+++ b/src/client/graphics/layers/UnitLayer.ts
@@ -82,6 +82,10 @@ export class UnitLayer implements Layer {
    * @returns Array of player's warships in range, sorted by distance (closest first)
    */
   private findWarshipsNearCell(cell: { x: number; y: number }): UnitView[] {
+    if (!this.game.isValidCoord(cell.x, cell.y)) {
+      // The cell coordinate were invalid (user probably clicked outside the map), therefore no warships can be found
+      return [];
+    }
     const clickRef = this.game.ref(cell.x, cell.y);
 
     // Make sure we have the current player