diff --git a/ocr-service/engines/kraken.py b/ocr-service/engines/kraken.py
index 5a5f4a98..60dfd47e 100644
--- a/ocr-service/engines/kraken.py
+++ b/ocr-service/engines/kraken.py
@@ -72,7 +72,7 @@ class _SenderModelRegistry:
         with self._lock:
             return len(self._cache)
 
-    def contains(self, model_path: str) -> bool:
+    def _contains(self, model_path: str) -> bool:
         with self._lock:
             return model_path in self._cache
 
diff --git a/ocr-service/test_sender_registry.py b/ocr-service/test_sender_registry.py
index be66090c..7cf7cd24 100644
--- a/ocr-service/test_sender_registry.py
+++ b/ocr-service/test_sender_registry.py
@@ -43,7 +43,7 @@ def test_lru_eviction_removes_least_recently_used():
 
     assert registry.size() == 2
     # 'a' was the least-recently-used and should be gone
-    assert not registry.contains("/app/models/sender_a.mlmodel")
+    assert not registry._contains("/app/models/sender_a.mlmodel")
 
 
 def test_invalidate_removes_entry_from_cache():