diff --git a/tests/plugins/test_libplugin.c b/tests/plugins/test_libplugin.c
index 6197116d8..ef62ab963 100644
--- a/tests/plugins/test_libplugin.c
+++ b/tests/plugins/test_libplugin.c
@@ -22,7 +22,7 @@ static struct command_result *json_helloworld(struct command *cmd,
 	if (!name)
 		name = name_option ? name_option : tal_strdup(tmpctx, "world");
 
-	return command_success_str(cmd, tal_fmt(tmpctx, "hello %s", name));
+	return command_success(cmd, json_out_obj(cmd, "hello", name));
 }
 
 static struct command_result *
diff --git a/tests/test_plugin.py b/tests/test_plugin.py
index cb3f6fe4d..212eb7cce 100644
--- a/tests/test_plugin.py
+++ b/tests/test_plugin.py
@@ -1412,15 +1412,15 @@ def test_libplugin(node_factory):
     l1.rpc.check("helloworld")
 
     # Test commands
-    assert l1.rpc.call("helloworld") == "hello world"
-    assert l1.rpc.call("helloworld", {"name": "test"}) == "hello test"
+    assert l1.rpc.call("helloworld") == {"hello": "world"}
+    assert l1.rpc.call("helloworld", {"name": "test"}) == {"hello": "test"}
     l1.stop()
     l1.daemon.opts["plugin"] = plugin
     l1.daemon.opts["name"] = "test_opt"
     l1.start()
-    assert l1.rpc.call("helloworld") == "hello test_opt"
+    assert l1.rpc.call("helloworld") == {"hello": "test_opt"}
     # But param takes over!
-    assert l1.rpc.call("helloworld", {"name": "test"}) == "hello test"
+    assert l1.rpc.call("helloworld", {"name": "test"}) == {"hello": "test"}
 
     # Test hooks and notifications
     l2 = node_factory.get_node()
@@ -1460,7 +1460,7 @@ def test_libplugin_deprecated(node_factory):
                                         'name-deprecated': 'test_opt depr',
                                         'allow-deprecated-apis': True})
 
-    assert l1.rpc.call("helloworld") == "hello test_opt depr"
+    assert l1.rpc.call("helloworld") == {"hello": "test_opt depr"}
     l1.rpc.help('testrpc-deprecated')
     assert l1.rpc.call("testrpc-deprecated") == l1.rpc.getinfo()