diff --git a/backend/scrape_proxy.py b/backend/scrape_proxy.py
index e1228ef..9fbedee 100644
--- a/backend/scrape_proxy.py
+++ b/backend/scrape_proxy.py
@@ -278,7 +278,7 @@ def api_metrics():
     # Cache size
     lines.append("# HELP cache_size Number of cached ZIP codes")
     lines.append("# TYPE cache_size gauge")
-    lines.append(f"zip_code_cache_size {len(zip_cache)}")
+    lines.append(f"zip_code_cache_size {len(scraper.zip_cache)}")
     lines.append("")
 
     # Kleinanzeigen response codes