diff --git a/grum/mainwin.py b/grum/mainwin.py
index c1d7037..749b201 100644
--- a/grum/mainwin.py
+++ b/grum/mainwin.py
@@ -13,6 +13,13 @@ from .shortcut import shortcut
 from .webview import WebView
 
 
+FILETYPE_FILTERS = [
+    "HDF5 files (*.h5)",
+    "All files (*)"
+]
+FILETYPE_FILTERS = ";;".join(FILETYPE_FILTERS)
+
+
 class MainWindow(QMainWindow):
 
     sig_make_new_plot = pyqtSignal(str, PlotDescription)
@@ -123,13 +130,7 @@ class MainWindow(QMainWindow):
 
 
     def on_file_save(self):
-        filters = [
-            "HDF5 files (*.h5)",
-            "All files (*)"
-        ]
-        filters = ";;".join(filters)
-
-        fn, _chosen_filter = QFileDialog.getSaveFileName(self, filter=filters)
+        fn, _chosen_filter = QFileDialog.getSaveFileName(self, filter=FILETYPE_FILTERS)
         if not fn:
             return
 
@@ -142,13 +143,7 @@ class MainWindow(QMainWindow):
 
 
     def on_file_open(self):
-        filters = [
-            "HDF5 files (*.h5)",
-            "All files (*)"
-        ]
-        filters = ";;".join(filters)
-
-        fns, _chosen_filter = QFileDialog.getOpenFileNames(self, filter=filters)
+        fns, _chosen_filter = QFileDialog.getOpenFileNames(self, filter=FILETYPE_FILTERS)
         if not fns:
             return