diff --git a/taskuary/cli.py b/taskuary/cli.py
index 8af78ba7..c9884afd 100644
--- a/taskuary/cli.py
+++ b/taskuary/cli.py
@@ -7,11 +7,14 @@
 def public_url(host, port) -> str:
     """0.0.0.0 / :: are bind addresses, not a place a browser can go."""
     shown = '127.0.0.1' if host in ('0.0.0.0', '::') else host
+    if ':' in shown and not shown.startswith('['): shown = f'[{shown}]'
     return f'http://{shown}:{port}'
 
 def _busy(host, port):
     probe = '127.0.0.1' if host in ('0.0.0.0', '::') else host
-    with socket.socket() as s: return s.connect_ex((probe, port)) == 0
+    try:
+        with socket.create_connection((probe.strip('[]'), port), timeout=0.2): return True
+    except OSError: return False
 
 def _is_taskuary(url):
     try:
diff --git a/tests/test_config.py b/tests/test_config.py
index 69fe834a..0dea2454 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -1,7 +1,7 @@
 """Config writer tests - the UI persists agents/settings, so save() must round-trip
 exactly through stdlib tomllib.
 """
-import os, unittest
+import os, socket, unittest
 from unittest import mock
 try: import tomllib
 except ImportError: import tomli as tomllib
@@ -91,6 +91,16 @@ def test_public_url_rewrites_wildcard_bind(self):
         self.assertEqual(cli.public_url('::', 7787), 'http://127.0.0.1:7787')
         self.assertEqual(cli.public_url('127.0.0.1', 7787), 'http://127.0.0.1:7787')
         self.assertEqual(cli.public_url('10.0.0.5', 9000), 'http://10.0.0.5:9000')
+        self.assertEqual(cli.public_url('::1', 7787), 'http://[::1]:7787')
+        try:
+            with socket.socket(socket.AF_INET6) as s:
+                s.bind(('::1', 0))
+                port = s.getsockname()[1]
+                self.assertFalse(cli._busy('::1', port))
+                s.listen(1)
+                self.assertTrue(cli._busy('::1', port))
+        except OSError:
+            pass
 
 
 if __name__ == '__main__':