diff --git a/icons/nix_quit.png b/icons/nixview_quit.png
similarity index 100%
rename from icons/nix_quit.png
rename to icons/nixview_quit.png
diff --git a/nixview/constants.py b/nixview/constants.py
index c8d3023..787e7fa 100644
--- a/nixview/constants.py
+++ b/nixview/constants.py
@@ -10,6 +10,8 @@ settings_recent_files_key = "/".join([organization, application, "recent_files"]
 settings_recent_file_max_count_key =  "/".join([organization, application, "recent_files_max_count"])
 settings_recent_file_max_count = 10
 
+io_chunksize = 10000000
+
 PACKAGE_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), os.pardir))
 ICONS_FOLDER = os.path.join(PACKAGE_ROOT, "icons")
 DOCS_ROOT_FILE = os.path.join(PACKAGE_ROOT, "docs", "index.md")
diff --git a/nixview/ui/centralwidget.py b/nixview/ui/centralwidget.py
index 8bec77f..275ae58 100644
--- a/nixview/ui/centralwidget.py
+++ b/nixview/ui/centralwidget.py
@@ -23,9 +23,9 @@ class CentralWidget(QWidget):
         self._stack.setCurrentIndex(1)
         self._file_view.update()
 
-    def plot_item(self, item):
+    def plot_item(self, item_descriptor):
         self._stack.setCurrentIndex(2)
-        self._plot_screen.plot(item)
+        self._plot_screen.plot(item_descriptor)
 
     def on_plot_close(self):
         self._stack.setCurrentIndex(1)