diff --git a/lib/wp/component-loader.c b/lib/wp/component-loader.c
index bf59b831..424b53c3 100644
--- a/lib/wp/component-loader.c
+++ b/lib/wp/component-loader.c
@@ -31,7 +31,7 @@ WP_DEFINE_LOCAL_LOG_TOPIC ("wp-comp-loader")
  */
 
 #define WP_MODULE_INIT_SYMBOL "wireplumber__module_init"
-typedef GObject *(*WpModuleInitFunc) (WpCore *, GVariant *, GError **);
+typedef GObject *(*WpModuleInitFunc) (WpCore *, WpSpaJson *, GError **);
 
 G_DEFINE_ABSTRACT_TYPE (WpComponentLoader, wp_component_loader, WP_TYPE_PLUGIN)
 
@@ -47,7 +47,7 @@ wp_component_loader_class_init (WpComponentLoaderClass * klass)
 
 static GObject *
 load_module (WpCore * core, const gchar * module_name,
-    GVariant * args, GError ** error)
+    WpSpaJson * args, GError ** error)
 {
   g_autofree gchar *module_path = NULL;
   GModule *gmodule;
@@ -99,7 +99,7 @@ wp_component_loader_find (WpCore * core, const gchar * type)
 
 static void
 wp_component_loader_load (WpComponentLoader * self, const gchar * component,
-    const gchar * type, GVariant * args, GAsyncReadyCallback callback,
+    const gchar * type, WpSpaJson * args, GAsyncReadyCallback callback,
     gpointer data)
 {
   g_return_if_fail (WP_IS_COMPONENT_LOADER (self));
@@ -132,17 +132,16 @@ on_object_loaded (WpObject *object, GAsyncResult *res, gpointer data)
  * \param self the core
  * \param component the module name or file name
  * \param type the type of the component
- * \param args (transfer floating)(nullable): additional arguments for the component,
- *   usually a dict or a string
+ * \param args (transfer none)(nullable): additional arguments for the component,
+ *   expected to be a JSON object
  * \param callback (scope async): the callback to call when the operation is done
  * \param data (closure): data to pass to \a callback
  */
 void
 wp_core_load_component (WpCore * self, const gchar * component,
-    const gchar * type, GVariant * args, GAsyncReadyCallback callback,
+    const gchar * type, WpSpaJson * args, GAsyncReadyCallback callback,
     gpointer data)
 {
-  g_autoptr (GVariant) args_ref = args ? g_variant_ref_sink (args) : NULL;
   g_autoptr (GTask) task = NULL;
   g_autoptr (WpComponentLoader) c = NULL;
 
@@ -153,7 +152,7 @@ wp_core_load_component (WpCore * self, const gchar * component,
     g_autoptr (GObject) o = NULL;
 
     /* load Module */
-    o = load_module (self, component, args_ref, &error);
+    o = load_module (self, component, args, &error);
     if (!o) {
       g_task_return_error (task, g_steal_pointer (&error));
       return;
diff --git a/lib/wp/component-loader.h b/lib/wp/component-loader.h
index 3c6267eb..7ff44387 100644
--- a/lib/wp/component-loader.h
+++ b/lib/wp/component-loader.h
@@ -10,6 +10,7 @@
 #define __WIREPLUMBER_COMPONENT_LOADER_H__
 
 #include "plugin.h"
+#include "spa-json.h"
 
 G_BEGIN_DECLS
 
@@ -29,7 +30,7 @@ struct _WpComponentLoaderClass
   gboolean (*supports_type) (WpComponentLoader * self, const gchar * type);
 
   void (*load) (WpComponentLoader * self, const gchar * component,
-      const gchar * type, GVariant * args, GAsyncReadyCallback callback,
+      const gchar * type, WpSpaJson * args, GAsyncReadyCallback callback,
       gpointer data);
 
   /*< private >*/
diff --git a/lib/wp/core.h b/lib/wp/core.h
index d62b51ba..6b1e6fca 100644
--- a/lib/wp/core.h
+++ b/lib/wp/core.h
@@ -12,6 +12,7 @@
 #include <gio/gio.h>
 #include "defs.h"
 #include "properties.h"
+#include "spa-json.h"
 
 G_BEGIN_DECLS
 
@@ -49,7 +50,7 @@ gchar *wp_core_get_vm_type (WpCore *self);
 
 WP_API
 void wp_core_load_component (WpCore * self, const gchar * component,
-    const gchar * type, GVariant * args, GAsyncReadyCallback callback,
+    const gchar * type, WpSpaJson * args, GAsyncReadyCallback callback,
     gpointer data);
 
 WP_API
diff --git a/modules/module-default-nodes-api.c b/modules/module-default-nodes-api.c
index eca4850a..f7e7fc4b 100644
--- a/modules/module-default-nodes-api.c
+++ b/modules/module-default-nodes-api.c
@@ -307,7 +307,7 @@ wp_default_nodes_api_class_init (WpDefaultNodesApiClass * klass)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (g_object_new (wp_default_nodes_api_get_type (),
       "name", "default-nodes-api",
diff --git a/modules/module-file-monitor-api.c b/modules/module-file-monitor-api.c
index 34d0677d..991bb44a 100644
--- a/modules/module-file-monitor-api.c
+++ b/modules/module-file-monitor-api.c
@@ -204,7 +204,7 @@ wp_file_monitor_api_class_init (WpFileMonitorApiClass * klass)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (g_object_new (wp_file_monitor_api_get_type (),
       "name", "file-monitor-api",
diff --git a/modules/module-logind.c b/modules/module-logind.c
index 26b64f99..43952536 100644
--- a/modules/module-logind.c
+++ b/modules/module-logind.c
@@ -134,7 +134,7 @@ wp_logind_class_init (WpLogindClass * klass)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (g_object_new (wp_logind_get_type (),
       "name", NAME,
diff --git a/modules/module-lua-scripting/module.c b/modules/module-lua-scripting/module.c
index a31a75a9..42faf1fa 100644
--- a/modules/module-lua-scripting/module.c
+++ b/modules/module-lua-scripting/module.c
@@ -173,7 +173,7 @@ on_script_loaded (WpObject *object, GAsyncResult *res, gpointer data)
 
 static void
 wp_lua_scripting_plugin_load (WpComponentLoader * cl, const gchar * component,
-    const gchar * type, GVariant * args, GAsyncReadyCallback callback,
+    const gchar * type, WpSpaJson * args, GAsyncReadyCallback callback,
     gpointer data)
 {
   WpLuaScriptingPlugin * self = WP_LUA_SCRIPTING_PLUGIN (cl);
@@ -238,7 +238,7 @@ wp_lua_scripting_plugin_class_init (WpLuaScriptingPluginClass * klass)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (g_object_new (wp_lua_scripting_plugin_get_type (),
       "name", "lua-scripting",
diff --git a/modules/module-lua-scripting/script.c b/modules/module-lua-scripting/script.c
index 945eb581..38b32272 100644
--- a/modules/module-lua-scripting/script.c
+++ b/modules/module-lua-scripting/script.c
@@ -29,7 +29,7 @@ struct _WpLuaScript
 
   lua_State *L;
   gchar *filename;
-  GVariant *args;
+  WpSpaJson *args;
 };
 
 enum {
@@ -64,7 +64,7 @@ wp_lua_script_finalize (GObject * object)
   wp_lua_script_cleanup (self);
   g_clear_pointer (&self->L, wplua_unref);
   g_clear_pointer (&self->filename, g_free);
-  g_clear_pointer (&self->args, g_variant_unref);
+  g_clear_pointer (&self->args, wp_spa_json_unref);
 
   G_OBJECT_CLASS (wp_lua_script_parent_class)->finalize (object);
 }
@@ -86,7 +86,7 @@ wp_lua_script_set_property (GObject * object, guint property_id,
     self->filename = g_value_dup_string (value);
     break;
   case PROP_ARGUMENTS:
-    self->args = g_value_dup_variant (value);
+    self->args = g_value_dup_boxed (value);
     break;
   default:
     G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
@@ -231,7 +231,7 @@ wp_lua_script_enable (WpPlugin * plugin, WpTransition * transition)
 
   /* push script arguments */
   if (self->args) {
-    wplua_gvariant_to_lua (self->L, self->args);
+    wplua_pushboxed (self->L, WP_TYPE_SPA_JSON, wp_spa_json_ref (self->args));
     nargs++;
   }
 
@@ -282,7 +282,7 @@ wp_lua_script_class_init (WpLuaScriptClass * klass)
           G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
 
   g_object_class_install_property (object_class, PROP_ARGUMENTS,
-      g_param_spec_variant ("arguments", "arguments", "arguments",
-          G_VARIANT_TYPE_VARDICT, NULL,
+      g_param_spec_boxed ("arguments", "arguments", "arguments",
+          WP_TYPE_SPA_JSON,
           G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
 }
diff --git a/modules/module-lua-scripting/wplua/boxed.c b/modules/module-lua-scripting/wplua/boxed.c
index 467e7305..83288319 100644
--- a/modules/module-lua-scripting/wplua/boxed.c
+++ b/modules/module-lua-scripting/wplua/boxed.c
@@ -30,6 +30,7 @@ _wplua_gboxed___index (lua_State *L)
       "expected userdata storing GValue<GBoxed>");
   GValue *obj_v = lua_touserdata (L, 1);
   const gchar *key = luaL_checkstring (L, 2);
+  GType type = G_VALUE_TYPE (obj_v);
   lua_CFunction func = NULL;
   GHashTable *vtables;
 
@@ -39,15 +40,15 @@ _wplua_gboxed___index (lua_State *L)
   lua_pop (L, 1);
 
   /* search in registered vtables */
-  if (!func) {
-    GType type = G_VALUE_TYPE (obj_v);
-    while (!func && type) {
-      luaL_Reg *reg = g_hash_table_lookup (vtables, GUINT_TO_POINTER (type));
-      func = find_method_in_luaL_Reg (reg, key);
-      type = g_type_parent (type);
-    }
+  while (!func && type) {
+    luaL_Reg *reg = g_hash_table_lookup (vtables, GUINT_TO_POINTER (type));
+    func = find_method_in_luaL_Reg (reg, key);
+    type = g_type_parent (type);
   }
 
+  wp_trace_boxed (type, g_value_get_boxed (obj_v),
+      "indexing GBoxed, looking for '%s', found: %p", key, func);
+
   if (func) {
     lua_pushcfunction (L, func);
     return 1;
diff --git a/modules/module-mixer-api.c b/modules/module-mixer-api.c
index f8e87fdf..3106da34 100644
--- a/modules/module-mixer-api.c
+++ b/modules/module-mixer-api.c
@@ -617,7 +617,7 @@ wp_mixer_api_class_init (WpMixerApiClass * klass)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (g_object_new (wp_mixer_api_get_type (),
       "name", "mixer-api",
diff --git a/modules/module-portal-permissionstore.c b/modules/module-portal-permissionstore.c
index 6f5bc26a..7683da25 100644
--- a/modules/module-portal-permissionstore.c
+++ b/modules/module-portal-permissionstore.c
@@ -305,7 +305,7 @@ wp_portal_permissionstore_plugin_class_init (
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (g_object_new (
       wp_portal_permissionstore_plugin_get_type(),
diff --git a/modules/module-reserve-device/plugin.c b/modules/module-reserve-device/plugin.c
index 469fe69f..86089536 100644
--- a/modules/module-reserve-device/plugin.c
+++ b/modules/module-reserve-device/plugin.c
@@ -267,7 +267,7 @@ wp_reserve_device_plugin_class_init (WpReserveDevicePluginClass * klass)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (g_object_new (wp_reserve_device_plugin_get_type (),
       "name", "reserve-device",
diff --git a/modules/module-settings.c b/modules/module-settings.c
index d50920f7..10dbeebf 100644
--- a/modules/module-settings.c
+++ b/modules/module-settings.c
@@ -339,15 +339,15 @@ wp_settings_plugin_class_init (WpSettingsPluginClass * klass)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
-  const gchar *metadata_name = "sm-settings";
+  g_autofree gchar *metadata_name = NULL;
   if (args)
-    metadata_name = g_variant_get_string (args, NULL);
+    wp_spa_json_object_get (args, "metadata-name", "s", &metadata_name, NULL);
 
   return G_OBJECT (g_object_new (wp_settings_plugin_get_type (),
       "name", "settings",
       "core", core,
-      "metadata-name", metadata_name,
+      "metadata-name", metadata_name ? metadata_name : "sm-settings",
       NULL));
 }
diff --git a/modules/module-si-audio-adapter.c b/modules/module-si-audio-adapter.c
index fc81c86d..0071b4f7 100644
--- a/modules/module-si-audio-adapter.c
+++ b/modules/module-si-audio-adapter.c
@@ -780,7 +780,7 @@ si_audio_adapter_linkable_init (WpSiLinkableInterface * iface)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (wp_si_factory_new_simple (SI_FACTORY_NAME,
       si_audio_adapter_get_type ()));
diff --git a/modules/module-si-audio-virtual.c b/modules/module-si-audio-virtual.c
index c652369f..00dbced5 100644
--- a/modules/module-si-audio-virtual.c
+++ b/modules/module-si-audio-virtual.c
@@ -358,7 +358,7 @@ si_audio_virtual_adapter_init (WpSiAdapterInterface * iface)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (wp_si_factory_new_simple (SI_FACTORY_NAME,
       si_audio_virtual_get_type ()));
diff --git a/modules/module-si-node.c b/modules/module-si-node.c
index 58fe256c..abadbf79 100644
--- a/modules/module-si-node.c
+++ b/modules/module-si-node.c
@@ -222,7 +222,7 @@ si_node_linkable_init (WpSiLinkableInterface * iface)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (wp_si_factory_new_simple (SI_FACTORY_NAME,
       si_node_get_type ()));
diff --git a/modules/module-si-standard-link.c b/modules/module-si-standard-link.c
index edf7e584..5a39d5e9 100644
--- a/modules/module-si-standard-link.c
+++ b/modules/module-si-standard-link.c
@@ -778,7 +778,7 @@ si_standard_link_link_init (WpSiLinkInterface * iface)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (wp_si_factory_new_simple (SI_FACTORY_NAME,
       si_standard_link_get_type ()));
diff --git a/modules/module-standard-event-source.c b/modules/module-standard-event-source.c
index dd4330dd..7e21e601 100644
--- a/modules/module-standard-event-source.c
+++ b/modules/module-standard-event-source.c
@@ -452,7 +452,7 @@ wp_standard_event_source_class_init (WpStandardEventSourceClass * klass)
 }
 
 WP_PLUGIN_EXPORT GObject *
-wireplumber__module_init (WpCore * core, GVariant * args, GError ** error)
+wireplumber__module_init (WpCore * core, WpSpaJson * args, GError ** error)
 {
   return G_OBJECT (g_object_new (wp_standard_event_source_get_type (),
       "name", "standard-event-source",
diff --git a/src/tools/wpexec.c b/src/tools/wpexec.c
index 9e78c934..d73d1d34 100644
--- a/src/tools/wpexec.c
+++ b/src/tools/wpexec.c
@@ -27,8 +27,8 @@ enum WpExitCode
 };
 
 static gchar * exec_script = NULL;
-static GVariantBuilder exec_args_b =
-    G_VARIANT_BUILDER_INIT (G_VARIANT_TYPE_VARDICT);
+static gchar *exec_args_s = NULL;
+static WpSpaJson *exec_args = NULL;
 
 static gboolean
 parse_exec_script_arg (const gchar *option_name, const gchar *value,
@@ -40,16 +40,17 @@ parse_exec_script_arg (const gchar *option_name, const gchar *value,
     return TRUE;
   }
 
-  g_auto(GStrv) tokens = g_strsplit (value, "=", 2);
-  if (!tokens[0] || *g_strstrip (tokens[0]) == '\0') {
-    g_set_error (error, WP_DOMAIN_DAEMON, WP_EXIT_USAGE,
-        "invalid script argument '%s'; must be in key=value format", value);
-    return FALSE;
+  /* the second argument is a json object with script arguments */
+  if (!exec_args) {
+    exec_args_s = g_strdup (value);
+    exec_args = wp_spa_json_new_from_string (exec_args_s);
+    if (!exec_args || !wp_spa_json_is_object (exec_args)) {
+      g_set_error (error, WP_DOMAIN_DAEMON, WP_EXIT_USAGE,
+          "script argument must be a JSON object");
+      return FALSE;
+    }
   }
 
-  g_variant_builder_add (&exec_args_b, "{sv}", tokens[0], tokens[1] ?
-          g_variant_new_string (g_strstrip (tokens[1])) :
-          g_variant_new_boolean (TRUE));
   return TRUE;
 }
 
@@ -146,8 +147,7 @@ wp_init_transition_execute_step (WpTransition * transition, guint step)
   }
 
   case STEP_ACTIVATE_SCRIPT: {
-    GVariant *args = g_variant_builder_end (&exec_args_b);
-    wp_core_load_component (core, exec_script, "script/lua", args,
+    wp_core_load_component (core, exec_script, "script/lua", exec_args,
           (GAsyncReadyCallback) on_plugin_loaded, self);
     break;
   }
diff --git a/tests/examples/interactive.lua b/tests/examples/interactive.lua
index 4d2e1dc5..96a4115c 100755
--- a/tests/examples/interactive.lua
+++ b/tests/examples/interactive.lua
@@ -10,21 +10,23 @@
 -- This is an example of an interactive script
 --
 -- Execute with:
---   wpexec ./interactive.lua option1=value1 option2=value2 ...
+--   wpexec ./interactive.lua '{ option1 = "value1" , option2 = "value2" }' ...
 -- or:
---   ./interactive.lua option1=value1 option2=value2
+--   ./interactive.lua '{ option1 = "value1" , option2 = "value2" }'
 -----------------------------------------------------------------------------
 
 --
 -- Collects arguments passed in from the command line
--- Assuming option1=value1 option2=value2 were passed, this will be a table
--- like this: { ["option1"] = "value1", ["option2"] = "value2" }
+-- Assuming '{ option1 = "value1" , option2 = "value2" }' were passed,
+-- this will be a table like this:
+-- { ["option1"] = "value1", ["option2"] = "value2" }
 --
 local argv = ...
+if argv then
+  argv = argv:parse()
 
-print ("Command-line arguments:")
-for k, v in pairs(argv) do
-  print ("\t" .. k .. ": " .. v)
+  print ("Command-line arguments:")
+  Debug.dump_table (argv)
 end
 
 --