diff --git a/src/diffuse/main.py b/src/diffuse/main.py
index 5e43ee4..a1c88fb 100644
--- a/src/diffuse/main.py
+++ b/src/diffuse/main.py
@@ -98,7 +98,7 @@ def __init__(self, sysconfigdir: str):
             'label',
             ord('L'),
             GLib.OptionFlags.NONE,
-            GLib.OptionArg.STRING,
+            GLib.OptionArg.STRING_ARRAY,
             _('Display <label> instead of the file name'),
             'label',
         )
@@ -323,7 +323,7 @@ def do_command_line(self, command_line):
             diff_window.prefs.setBool('align_ignore_whitespace', True)
             diff_window.preferences_updated()
         if 'label' in options:
-            labels.append(options['label'])
+            labels.extend(options['label'])
         if 'line' in options:
             try:
                 opts['line'] = int(options['line'])