diff --git a/PFERD/download_summary.py b/PFERD/download_summary.py
index ae011c8..28d51b5 100644
--- a/PFERD/download_summary.py
+++ b/PFERD/download_summary.py
@@ -11,38 +11,59 @@ class DownloadSummary:
     """
 
     def __init__(self) -> None:
-        self.new_files: List[Path] = []
-        self.modified_files: List[Path] = []
-        self.deleted_files: List[Path] = []
+        self._new_files: List[Path] = []
+        self._modified_files: List[Path] = []
+        self._deleted_files: List[Path] = []
+
+    @property
+    def new_files(self) -> List[Path]:
+        """
+        Returns all new files.
+        """
+        return self._new_files.copy()
+
+    @property
+    def modified_files(self) -> List[Path]:
+        """
+        Returns all modified files.
+        """
+        return self._modified_files.copy()
+
+    @property
+    def deleted_files(self) -> List[Path]:
+        """
+        Returns all deleted files.
+        """
+        return self._deleted_files.copy()
 
     def merge(self, summary: 'DownloadSummary') -> None:
         """
         Merges ourselves with the passed summary. Modifies this object, but not the passed one.
         """
-        self.new_files += summary.new_files
-        self.modified_files += summary.modified_files
-        self.deleted_files += summary.deleted_files
+        self._new_files += summary.new_files
+        self._modified_files += summary.modified_files
+        self._deleted_files += summary.deleted_files
 
     def add_deleted_file(self, path: Path) -> None:
         """
         Registers a file as deleted.
         """
-        self.deleted_files.append(path)
+        self._deleted_files.append(path)
 
     def add_modified_file(self, path: Path) -> None:
         """
         Registers a file as changed.
         """
-        self.modified_files.append(path)
+        self._modified_files.append(path)
 
     def add_new_file(self, path: Path) -> None:
         """
         Registers a file as new.
         """
-        self.new_files.append(path)
+        self._new_files.append(path)
 
     def has_updates(self) -> bool:
         """
         Returns whether this summary has any updates.
         """
-        return bool(self.new_files or self.modified_files or self.deleted_files)
+        return bool(self._new_files or self._modified_files or self._deleted_files)