diff --git a/app/Services/ZaarboxPriceService.php b/app/Services/ZaarboxPriceService.php
index 040decb..031349f 100644
--- a/app/Services/ZaarboxPriceService.php
+++ b/app/Services/ZaarboxPriceService.php
@@ -9,7 +9,7 @@ use Illuminate\Support\Facades\Log;
 
 class ZaarboxPriceService
 {
-    public const CACHE_KEY = 'zaarbox_gold_prices';
+    private const CACHE_KEY_PREFIX = 'zaarbox_gold_prices';
 
     private const CACHE_TTL_MINUTES = 35;
 
@@ -33,9 +33,14 @@ class ZaarboxPriceService
         return $chartId ?: self::HISTORY_ID;
     }
 
+    private function cacheKey(): string
+    {
+        return self::CACHE_KEY_PREFIX . ':' . $this->historyId();
+    }
+
     public function getAllPrices(): array
     {
-        $cached = Cache::get(self::CACHE_KEY);
+        $cached = Cache::get($this->cacheKey());
 
         if (is_array($cached) && isset($cached['prices'])) {
             return $cached['prices'];
@@ -48,7 +53,7 @@ class ZaarboxPriceService
     {
         $prices = $this->fetchAllPrices();
 
-        Cache::put(self::CACHE_KEY, [
+        Cache::put($this->cacheKey(), [
             'prices' => $prices,
             'refreshed_at' => now()->toIso8601String(),
         ], now()->addMinutes(self::CACHE_TTL_MINUTES));