diff --git a/tests/test_config_overrides.py b/tests/test_config_overrides.py
index bc3f606..08366ce 100755
--- a/tests/test_config_overrides.py
+++ b/tests/test_config_overrides.py
@@ -63,6 +63,30 @@ def test_update_from_args_controller_host(self):
         self.assertEqual(self.config.get("controller", "host"), "foo")
         self.assertEqual(self.config.getint("controller", "port"), 2149)
 
+        parser = zeekclient.cli.create_parser()
+        args = parser.parse_args(["--controller", "127.0.0.1"])
+        self.config.update_from_args(args)
+        self.assertEqual(self.config.get("controller", "host"), "127.0.0.1")
+        self.assertEqual(self.config.getint("controller", "port"), 2149)
+
+        parser = zeekclient.cli.create_parser()
+        args = parser.parse_args(["--controller", "127.0.0.1:"])
+        self.config.update_from_args(args)
+        self.assertEqual(self.config.get("controller", "host"), "127.0.0.1")
+        self.assertEqual(self.config.getint("controller", "port"), 2149)
+
+        parser = zeekclient.cli.create_parser()
+        args = parser.parse_args(["--controller", "[fe80::1]"])
+        self.config.update_from_args(args)
+        self.assertEqual(self.config.get("controller", "host"), "[fe80::1]")
+        self.assertEqual(self.config.getint("controller", "port"), 2149)
+
+        parser = zeekclient.cli.create_parser()
+        args = parser.parse_args(["--controller", "[fe80::1]:"])
+        self.config.update_from_args(args)
+        self.assertEqual(self.config.get("controller", "host"), "[fe80::1]")
+        self.assertEqual(self.config.getint("controller", "port"), 2149)
+
     def test_update_from_args_controller_port(self):
         parser = zeekclient.cli.create_parser()
         args = parser.parse_args(["--controller", ":2222"])
@@ -76,3 +100,15 @@ def test_update_from_args_controller_hostport(self):
         self.config.update_from_args(args)
         self.assertEqual(self.config.get("controller", "host"), "foo")
         self.assertEqual(self.config.getint("controller", "port"), 2222)
+
+        parser = zeekclient.cli.create_parser()
+        args = parser.parse_args(["--controller", "127.0.0.1:2222"])
+        self.config.update_from_args(args)
+        self.assertEqual(self.config.get("controller", "host"), "127.0.0.1")
+        self.assertEqual(self.config.getint("controller", "port"), 2222)
+
+        parser = zeekclient.cli.create_parser()
+        args = parser.parse_args(["--controller", "[fe80::1]:2222"])
+        self.config.update_from_args(args)
+        self.assertEqual(self.config.get("controller", "host"), "[fe80::1]")
+        self.assertEqual(self.config.getint("controller", "port"), 2222)
diff --git a/zeekclient/config.py b/zeekclient/config.py
index 9200250..461f699 100644
--- a/zeekclient/config.py
+++ b/zeekclient/config.py
@@ -118,16 +118,30 @@ def update_from_args(self, args):
         # The `--controller` argument is a shortcut for two `--set` arguments that
         # set controller host and port, so update these manually:
         if args.controller:
-            host_port = args.controller.split(":", 1)
-            if len(host_port) != 2 or not host_port[1]:
+            if ":" not in args.controller:
+                host = args.controller
+                port = ""
+            else:
+                (host, _, port) = args.controller.rpartition(":")
+                if host.count(":") >= 1:
+                    # We likely have an IPv6 address
+                    if not host.startswith("["):
+                        raise ValueError(
+                            "IPv6 addresses must be surrounded by brackets: [<ipv6>]:<port>"
+                        )
+                    if port.endswith("]"):
+                        host = host + ":" + port
+                        port = ""
+
+            if port == "":
                 # It's just a hostname
-                self.set("controller", "host", host_port[0])
-            elif not host_port[0]:
+                self.set("controller", "host", host)
+            elif host == "":
                 # It's just a port (as ":<port>")
-                self.set("controller", "port", host_port[1])
+                self.set("controller", "port", port)
             else:
-                self.set("controller", "host", host_port[0])
-                self.set("controller", "port", host_port[1])
+                self.set("controller", "host", host)
+                self.set("controller", "port", port)
 
         # --verbose/-v/-vvv etc set a numeric verbosity level:
         if args.verbose: