diff --git a/dangerzone/__init__.py b/dangerzone/__init__.py
index 902d49a..fccc6b3 100644
--- a/dangerzone/__init__.py
+++ b/dangerzone/__init__.py
@@ -63,26 +63,50 @@ def main(filename):
         docker_installer.start()
         return
 
-    # Main window
-    main_window = MainWindow(common)
+    windows = []
+    doc_opened = False
 
-    def select_document(filename):
-        # Validate filename
-        filename = os.path.abspath(os.path.expanduser(filename))
-        try:
-            open(filename, "rb")
-        except FileNotFoundError:
-            print("File not found")
-            return False
-        except PermissionError:
-            print("Permission denied")
-            return False
-        common.set_document_filename(filename)
-        main_window.doc_selection_widget.document_selected.emit()
+    # Open a document in a window
+    def select_document(filename=None):
+        print(f"select_document, filename={filename}")
+        new_window = MainWindow(common)
+
+        if filename:
+            # Validate filename
+            filename = os.path.abspath(os.path.expanduser(filename))
+            try:
+                open(filename, "rb")
+            except FileNotFoundError:
+                print("File not found")
+                return False
+            except PermissionError:
+                print("Permission denied")
+                return False
+            common.set_document_filename(filename)
+            new_window.doc_selection_widget.document_selected.emit()
+
+        windows.append(new_window)
+        doc_opened = True
         return True
 
     # If filename is passed as an argument, open it
-    if filename is not None:
+    if filename is None:
+        if platform.system() == "Darwin":
+            # Wait 0.5 seconds to see if we can an open document event, and if not open a new window without a document
+            def open_window_if_not_already_open():
+                if not doc_opened:
+                    select_document()
+
+            timer = QtCore.QTimer()
+            timer.setSingleShot(True)
+            timer.setInterval(500)
+            timer.timeout.connect(open_window_if_not_already_open)
+            timer.start()
+        else:
+            # Open a new window without a document
+            select_document()
+    else:
+        # Try opening a window with the docoument selected
         if not select_document(filename):
             return False
 
diff --git a/dangerzone/main_window.py b/dangerzone/main_window.py
index 4d6e231..15440ef 100644
--- a/dangerzone/main_window.py
+++ b/dangerzone/main_window.py
@@ -79,4 +79,3 @@ class MainWindow(QtWidgets.QMainWindow):
 
     def closeEvent(self, e):
         e.accept()
-        self.common.app.quit()