diff --git a/libsecret/secret-backend.c b/libsecret/secret-backend.c
index 6ce2645..946b342 100644
--- a/libsecret/secret-backend.c
+++ b/libsecret/secret-backend.c
@@ -204,7 +204,7 @@ on_ensure_for_flags (GObject *source_object,
 /**
  * secret_backend_get:
  * @flags: flags for which service functionality to ensure is initialized
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
diff --git a/libsecret/secret-collection.c b/libsecret/secret-collection.c
index efd3ccb..dbd7165 100644
--- a/libsecret/secret-collection.c
+++ b/libsecret/secret-collection.c
@@ -777,7 +777,7 @@ on_load_item (GObject *source,
 /**
  * secret_collection_load_items:
  * @self: the secret collection
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -870,7 +870,7 @@ secret_collection_load_items_finish (SecretCollection *self,
 /**
  * secret_collection_load_items_sync:
  * @self: the secret collection
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Ensure that the #SecretCollection proxy has loaded all the items present
@@ -1061,7 +1061,7 @@ _secret_collection_properties_new (const gchar *label)
  * @label: label for the new collection
  * @alias: (nullable): alias to assign to the collection
  * @flags: currently unused
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -1159,7 +1159,7 @@ secret_collection_create_finish (GAsyncResult *result,
  * @label: label for the new collection
  * @alias: (nullable): alias to assign to the collection
  * @flags: currently unused
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Create a new collection in the secret service.
@@ -1400,7 +1400,7 @@ on_search_paths (GObject *source,
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): search for items matching these attributes
  * @flags: search option flags
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -1534,7 +1534,7 @@ collection_load_items_sync (SecretCollection *self,
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): search for items matching these attributes
  * @flags: search option flags
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place error on failure
  *
  * Search for items matching the @attributes in the @collection.
@@ -1625,7 +1625,7 @@ on_service_delete_path (GObject *source,
 /**
  * secret_collection_delete:
  * @self: a collection
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -1687,7 +1687,7 @@ secret_collection_delete_finish (SecretCollection *self,
 /**
  * secret_collection_delete_sync:
  * @self: a collection
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Delete this collection.
@@ -1841,7 +1841,7 @@ secret_collection_get_label (SecretCollection *self)
  * secret_collection_set_label:
  * @self: a collection
  * @label: a new label
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -1891,7 +1891,7 @@ secret_collection_set_label_finish (SecretCollection *self,
  * secret_collection_set_label_sync:
  * @self: a collection
  * @label: a new label
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place error on failure
  *
  * Set the label of this collection.
diff --git a/libsecret/secret-item.c b/libsecret/secret-item.c
index 7e83585..efab923 100644
--- a/libsecret/secret-item.c
+++ b/libsecret/secret-item.c
@@ -723,7 +723,7 @@ item_properties_new (const gchar *label,
  * @label: label for the new item
  * @value: secret value for the new item
  * @flags: flags for the creation of the new item
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -818,7 +818,7 @@ secret_item_create_finish (GAsyncResult *result,
  * @label: label for the new item
  * @value: secret value for the new item
  * @flags: flags for the creation of the new item
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Create a new item in the secret service.
@@ -964,7 +964,7 @@ secret_item_delete_finish (SecretItem *self,
 /**
  * secret_item_delete_sync:
  * @self: an item
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Delete this secret item.
@@ -1211,7 +1211,7 @@ secret_item_load_secret_finish (SecretItem *self,
 /**
  * secret_item_load_secret_sync:
  * @self: an item
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place error on failure
  *
  * Load the secret value of this item.
@@ -1388,7 +1388,7 @@ on_loads_secrets_session (GObject *source,
 /**
  * secret_item_load_secrets:
  * @items: (element-type Secret.Item): the items to retrieve secrets for
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -1483,7 +1483,7 @@ secret_item_load_secrets_finish (GAsyncResult *result,
 /**
  * secret_item_load_secrets_sync:
  * @items: (element-type Secret.Item): the items to retrieve secrets for
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Load the secret values for a secret item stored in the service.
@@ -1588,7 +1588,7 @@ on_set_ensure_session (GObject *source,
  * secret_item_set_secret:
  * @self: an item
  * @value: a new secret value
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -1652,7 +1652,7 @@ secret_item_set_secret_finish (SecretItem *self,
  * secret_item_set_secret_sync:
  * @self: an item
  * @value: a new secret value
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place error on failure
  *
  * Set the secret value of this item.
@@ -1758,7 +1758,7 @@ secret_item_get_attributes (SecretItem *self)
  * @self: an item
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): a new set of attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the asynchronous operation completes
  * @user_data: data to pass to the callback
  *
@@ -1822,7 +1822,7 @@ secret_item_set_attributes_finish (SecretItem *self,
  * @self: an item
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): a new set of attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place error on failure
  *
  * Set the attributes of this item.
@@ -1888,7 +1888,7 @@ secret_item_get_label (SecretItem *self)
  * secret_item_set_label:
  * @self: an item
  * @label: a new label
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -1938,7 +1938,7 @@ secret_item_set_label_finish (SecretItem *self,
  * secret_item_set_label_sync:
  * @self: an item
  * @label: a new label
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place error on failure
  *
  * Set the label of this item.
diff --git a/libsecret/secret-methods.c b/libsecret/secret-methods.c
index cfa1260..528437f 100644
--- a/libsecret/secret-methods.c
+++ b/libsecret/secret-methods.c
@@ -263,7 +263,7 @@ on_search_service (GObject *source,
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): search for items matching these attributes
  * @flags: search option flags
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -407,7 +407,7 @@ service_load_items_sync (SecretService *service,
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): search for items matching these attributes
  * @flags: search option flags
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place error on failure
  *
  * Search for items matching the @attributes. All collections are searched.
@@ -728,7 +728,7 @@ service_xlock_finish (SecretService *service,
  * secret_service_lock:
  * @service: (nullable): the secret service
  * @objects: (element-type Gio.DBusProxy): the items or collections to lock
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -789,7 +789,7 @@ secret_service_lock_finish (SecretService *service,
  * secret_service_lock_sync:
  * @service: (nullable): the secret service
  * @objects: (element-type Gio.DBusProxy): the items or collections to lock
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @locked: (out) (element-type Gio.DBusProxy) (transfer full) (nullable) (optional):
  *          location to place list of items or collections that were locked
  * @error: location to place an error on failure
@@ -842,7 +842,7 @@ secret_service_lock_sync (SecretService *service,
  * secret_service_unlock:
  * @service: (nullable): the secret service
  * @objects: (element-type Gio.DBusProxy): the items or collections to unlock
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -903,7 +903,7 @@ secret_service_unlock_finish (SecretService *service,
  * secret_service_unlock_sync:
  * @service: (nullable): the secret service
  * @objects: (element-type Gio.DBusProxy): the items or collections to unlock
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @unlocked: (out) (element-type Gio.DBusProxy) (transfer full) (nullable) (optional):
  *            location to place list of items or collections that were unlocked
  * @error: location to place an error on failure
@@ -1109,7 +1109,7 @@ on_store_service (GObject *source,
  *              collection where to store the secret
  * @label: label for the secret
  * @value: the secret value
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1227,7 +1227,7 @@ secret_service_store_finish (SecretService *service,
  *              collection where to store the secret
  * @label: label for the secret
  * @value: the secret value
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Store a secret value in the secret service.
@@ -1424,7 +1424,7 @@ on_lookup_service (GObject *source,
  * @service: (nullable): the secret service
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1522,7 +1522,7 @@ secret_service_lookup_finish (SecretService *service,
  * @service: (nullable): the secret service
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Lookup a secret value in the secret service.
@@ -1675,7 +1675,7 @@ on_delete_service (GObject *source,
  * @service: (nullable): the secret service
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1772,7 +1772,7 @@ secret_service_clear_finish (SecretService *service,
  * @service: (nullable): the secret service
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Remove unlocked items which match the attributes from the secret service.
diff --git a/libsecret/secret-password.c b/libsecret/secret-password.c
index a226bfb..6fc7755 100644
--- a/libsecret/secret-password.c
+++ b/libsecret/secret-password.c
@@ -51,7 +51,7 @@
  *              collection where to store the secret
  * @label: label for the secret
  * @password: the null-terminated password to store
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  * @...: the attribute keys and values, terminated with %NULL
@@ -183,7 +183,7 @@ on_store_backend (GObject *source,
  *              collection where to store the secret
  * @label: label for the secret
  * @password: the null-terminated password to store
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: (scope async): called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -243,7 +243,7 @@ secret_password_storev (const SecretSchema *schema,
  *              collection where to store the secret
  * @label: label for the secret
  * @value: a #SecretValue
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  * @...: the attribute keys and values, terminated with %NULL
@@ -297,7 +297,7 @@ secret_password_store_binary (const SecretSchema *schema,
  *              collection where to store the secret
  * @label: label for the secret
  * @value: a #SecretValue
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: (scope async): called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -372,7 +372,7 @@ secret_password_store_finish (GAsyncResult *result,
  *              collection where to store the secret
  * @label: label for the secret
  * @password: the null-terminated password to store
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  * @...: the attribute keys and values, terminated with %NULL
  *
@@ -437,7 +437,7 @@ secret_password_store_sync (const SecretSchema *schema,
  *              collection where to store the secret
  * @label: label for the secret
  * @password: the null-terminated password to store
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Store a password in the secret service.
@@ -501,7 +501,7 @@ secret_password_storev_sync (const SecretSchema *schema,
  *              collection where to store the secret
  * @label: label for the secret
  * @value: a #SecretValue
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  * @...: the attribute keys and values, terminated with %NULL
  *
@@ -559,7 +559,7 @@ secret_password_store_binary_sync (const SecretSchema *schema,
  *              collection where to store the secret
  * @label: label for the secret
  * @value: a #SecretValue
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Store a password in the secret service.
@@ -615,7 +615,7 @@ secret_password_storev_binary_sync (const SecretSchema *schema,
 /**
  * secret_password_lookup: (skip)
  * @schema: the schema for the attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  * @...: the attribute keys and values, terminated with %NULL
@@ -731,7 +731,7 @@ on_lookup_backend (GObject *source,
  * secret_password_lookupv: (rename-to secret_password_lookup)
  * @schema: (nullable): the schema for attributes
  * @attributes: (element-type utf8 utf8) (transfer full): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: (scope async): called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -848,7 +848,7 @@ secret_password_lookup_finish (GAsyncResult *result,
 /**
  * secret_password_lookup_sync: (skip)
  * @schema: the schema for the attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  * @...: the attribute keys and values, terminated with %NULL
  *
@@ -900,7 +900,7 @@ secret_password_lookup_sync (const SecretSchema *schema,
 /**
  * secret_password_lookup_nonpageable_sync: (skip)
  * @schema: the schema for the attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  * @...: the attribute keys and values, terminated with %NULL
  *
@@ -953,7 +953,7 @@ secret_password_lookup_nonpageable_sync (const SecretSchema *schema,
  * secret_password_lookupv_nonpageable_sync: (skip)
  * @schema: (nullable): the schema for attributes
  * @attributes: (element-type utf8 utf8): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Lookup a password in the secret service.
@@ -1004,7 +1004,7 @@ secret_password_lookupv_nonpageable_sync (const SecretSchema *schema,
 /**
  * secret_password_lookup_binary_sync: (skip)
  * @schema: the schema for the attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  * @...: the attribute keys and values, terminated with %NULL
  *
@@ -1055,7 +1055,7 @@ secret_password_lookup_binary_sync (const SecretSchema *schema,
  * secret_password_lookupv_binary_sync: (skip)
  * @schema: (nullable): the schema for attributes
  * @attributes: (element-type utf8 utf8): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Lookup a password in the secret service.
@@ -1108,7 +1108,7 @@ secret_password_lookupv_binary_sync (const SecretSchema *schema,
  * secret_password_lookupv_sync: (rename-to secret_password_lookup_sync)
  * @schema: (nullable): the schema for attributes
  * @attributes: (element-type utf8 utf8): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Lookup a password in the secret service.
@@ -1159,7 +1159,7 @@ secret_password_lookupv_sync (const SecretSchema *schema,
 /**
  * secret_password_clear:
  * @schema: the schema for the attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  * @...: the attribute keys and values, terminated with %NULL
@@ -1273,7 +1273,7 @@ on_clear_backend (GObject *source,
  * secret_password_clearv: (rename-to secret_password_clear)
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8) (transfer full): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: (scope async): called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1336,7 +1336,7 @@ secret_password_clear_finish (GAsyncResult *result,
 /**
  * secret_password_clear_sync:
  * @schema: the schema for the attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  * @...: the attribute keys and values, terminated with %NULL
  *
@@ -1388,7 +1388,7 @@ secret_password_clear_sync (const SecretSchema* schema,
  * secret_password_clearv_sync: (rename-to secret_password_clear_sync)
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): the attribute keys and values
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Remove unlocked matching passwords from the secret service.
@@ -1439,7 +1439,7 @@ secret_password_clearv_sync (const SecretSchema *schema,
  * secret_password_search: (skip)
  * @schema: the schema for the attributes
  * @flags: search option flags
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  * @...: the attribute keys and values, terminated with %NULL
@@ -1563,7 +1563,7 @@ on_search_backend (GObject *source,
  * @schema: (nullable): the schema for attributes
  * @attributes: (element-type utf8 utf8) (transfer full): the attribute keys and values
  * @flags: search option flags
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: (scope async): called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1631,7 +1631,7 @@ secret_password_search_finish (GAsyncResult *result,
  * secret_password_search_sync: (skip)
  * @schema: the schema for the attributes
  * @flags: search option flags
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  * @...: the attribute keys and values, terminated with %NULL
  *
@@ -1688,7 +1688,7 @@ secret_password_search_sync (const SecretSchema *schema,
  * @schema: (nullable): the schema for attributes
  * @attributes: (element-type utf8 utf8): the attribute keys and values
  * @flags: search option flags
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Search for items in the secret service.
diff --git a/libsecret/secret-paths.c b/libsecret/secret-paths.c
index 2218fdf..cc9ebae 100644
--- a/libsecret/secret-paths.c
+++ b/libsecret/secret-paths.c
@@ -44,7 +44,7 @@
  * @service: (nullable): a secret service object
  * @collection_path: the D-Bus path of the collection
  * @flags: options for the collection initialization
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -123,7 +123,7 @@ secret_collection_new_for_dbus_path_finish (GAsyncResult *result,
  * @service: (nullable): a secret service object
  * @collection_path: the D-Bus path of the collection
  * @flags: options for the collection initialization
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Get a new collection proxy for a collection in the secret service.
@@ -173,7 +173,7 @@ secret_collection_new_for_dbus_path_sync (SecretService *service,
  * @service: (nullable): a secret service object
  * @item_path: the D-Bus path of the collection
  * @flags: initialization flags for the new item
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -251,7 +251,7 @@ secret_item_new_for_dbus_path_finish (GAsyncResult *result,
  * @service: (nullable): a secret service object
  * @item_path: the D-Bus path of the item
  * @flags: initialization flags for the new item
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Get a new item proxy for a secret item in the secret service.
@@ -322,7 +322,7 @@ on_search_items_complete (GObject *source,
  * @collection: the secret collection
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): search for items matching these attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -418,7 +418,7 @@ secret_collection_search_for_dbus_paths_finish (SecretCollection *collection,
  * @collection: the secret collection
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): search for items matching these attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place error on failure
  *
  * Search for items matching the @attributes in @collection, and return their
@@ -473,7 +473,7 @@ secret_collection_search_for_dbus_paths_sync (SecretCollection *collection,
  * @self: the secret service
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): search for items matching these attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -606,7 +606,7 @@ secret_service_search_for_dbus_paths_finish (SecretService *self,
  * @self: the secret service
  * @schema: (nullable): the schema for the attributes
  * @attributes: (element-type utf8 utf8): search for items matching these attributes
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @unlocked: (out) (transfer full) (array zero-terminated=1) (optional) (nullable):
  *            location to place an array of D-Bus object paths for matching
  *            items which were locked.
@@ -729,7 +729,7 @@ on_get_secrets_session (GObject *source,
  * secret_service_get_secret_for_dbus_path: (skip)
  * @self: the secret service
  * @item_path: the D-Bus path to item to retrieve secret for
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -812,7 +812,7 @@ secret_service_get_secret_for_dbus_path_finish (SecretService *self,
  * secret_service_get_secret_for_dbus_path_sync: (skip)
  * @self: the secret service
  * @item_path: the D-Bus path to item to retrieve secret for
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Get the secret value for a secret item stored in the service.
@@ -865,7 +865,7 @@ secret_service_get_secret_for_dbus_path_sync (SecretService *self,
  * secret_service_get_secrets_for_dbus_paths: (skip)
  * @self: the secret service
  * @item_paths: the D-Bus paths to items to retrieve secrets for
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -949,7 +949,7 @@ secret_service_get_secrets_for_dbus_paths_finish (SecretService *self,
  * secret_service_get_secrets_for_dbus_paths_sync: (skip)
  * @self: the secret service
  * @item_paths: the D-Bus paths to items to retrieve secrets for
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Get the secret values for a secret item stored in the service.
@@ -1149,7 +1149,7 @@ _secret_service_xlock_paths_finish (SecretService *self,
  * secret_service_lock_dbus_paths_sync: (skip)
  * @self: the secret service
  * @paths: (array zero-terminated=1): the D-Bus object paths of the items or collections to lock
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @locked: (out) (array zero-terminated=1) (transfer full) (optional) (nullable):
  *          location to place array of D-Bus paths of items or collections
  *          that were locked
@@ -1208,7 +1208,7 @@ secret_service_lock_dbus_paths_sync (SecretService *self,
  * secret_service_lock_dbus_paths: (skip)
  * @self: the secret service
  * @paths: (array zero-terminated=1): the D-Bus paths for items or collections to lock
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -1279,7 +1279,7 @@ secret_service_lock_dbus_paths_finish (SecretService *self,
  * @self: the secret service
  * @paths: (array zero-terminated=1): the D-Bus object paths of the items or
  *         collections to unlock
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @unlocked: (out) (array zero-terminated=1) (transfer full) (optional) (nullable):
  *            location to place array of D-Bus paths of items or collections
  *            that were unlocked
@@ -1339,7 +1339,7 @@ secret_service_unlock_dbus_paths_sync (SecretService *self,
  * @self: the secret service
  * @paths: (array zero-terminated=1): the D-Bus paths for items or
  *         collections to unlock
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to pass to the callback
  *
@@ -1533,7 +1533,7 @@ _secret_service_delete_path_finish (SecretService *self,
  * secret_service_delete_item_dbus_path: (skip)
  * @self: the secret service
  * @item_path: the D-Bus path of item to delete
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1585,7 +1585,7 @@ secret_service_delete_item_dbus_path_finish (SecretService *self,
  * secret_service_delete_item_dbus_path_sync: (skip)
  * @self: the secret service
  * @item_path: the D-Bus path of item to delete
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Delete a secret item from the secret service.
@@ -1708,7 +1708,7 @@ on_create_collection_called (GObject *source,
  * @alias: (nullable): an alias to check for before creating the new
  *         collection, or to assign to the new collection
  * @flags: not currently used
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1825,7 +1825,7 @@ secret_service_create_collection_dbus_path_finish (SecretService *self,
  * @alias: (nullable): an alias to check for before creating the new
  *         collection, or to assign to the new collection
  * @flags: not currently used
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Create a new collection in the secret service and return its path.
@@ -2011,7 +2011,7 @@ on_create_item_session (GObject *source,
  *              for the new collection
  * @value: the secret value to store in the item
  * @flags: flags for the creation of the new item
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -2133,7 +2133,7 @@ _secret_service_create_item_dbus_path_finish_raw (GAsyncResult *result,
  *              for the new collection
  * @value: the secret value to store in the item
  * @flags: flags for the creation of the new item
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Create a new item in a secret service collection and return its D-Bus
@@ -2445,7 +2445,7 @@ secret_service_set_alias_to_dbus_path_sync (SecretService *self,
  * secret_service_prompt_at_dbus_path_sync: (skip)
  * @self: the secret service
  * @prompt_path: the D-Bus object path of the prompt
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @return_type: (nullable): the variant type of the prompt result
  * @error: location to place error on failure
  *
@@ -2493,7 +2493,7 @@ secret_service_prompt_at_dbus_path_sync (SecretService *self,
  * @self: the secret service
  * @prompt_path: the D-Bus object path of the prompt
  * @return_type: (nullable): the variant type of the prompt result
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
diff --git a/libsecret/secret-prompt.c b/libsecret/secret-prompt.c
index 2ee28a8..e8d8409 100644
--- a/libsecret/secret-prompt.c
+++ b/libsecret/secret-prompt.c
@@ -121,7 +121,7 @@ _secret_prompt_instance (SecretService *service,
  * secret_prompt_run:
  * @self: a prompt
  * @window_id: (nullable): string form of XWindow id for parent window to be transient for
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @return_type: the variant type of the prompt result
  * @error: location to place an error on failure
  *
@@ -181,7 +181,7 @@ secret_prompt_run (SecretPrompt *self,
  * secret_prompt_perform_sync:
  * @self: a prompt
  * @window_id: (nullable): string form of XWindow id for parent window to be transient for
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @return_type: the variant type of the prompt result
  * @error: location to place an error on failure
  *
@@ -410,7 +410,7 @@ on_prompt_cancelled (GCancellable *cancellable,
  * @self: a prompt
  * @window_id: (nullable): string form of XWindow id for parent window to be transient for
  * @return_type: the variant type of the prompt result
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
diff --git a/libsecret/secret-service.c b/libsecret/secret-service.c
index b367fda..c2abbc2 100644
--- a/libsecret/secret-service.c
+++ b/libsecret/secret-service.c
@@ -947,7 +947,7 @@ secret_service_backend_iface (SecretBackendInterface *iface)
 /**
  * secret_service_get:
  * @flags: flags for which service functionality to ensure is initialized
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1045,7 +1045,7 @@ secret_service_get_finish (GAsyncResult *result,
 /**
  * secret_service_get_sync:
  * @flags: flags for which service functionality to ensure is initialized
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Get a #SecretService proxy for the Secret Service. If such a proxy object
@@ -1111,7 +1111,7 @@ secret_service_disconnect (void)
  * @service_gtype: the GType of the new secret service
  * @service_bus_name: (nullable): the D-Bus service name of the secret service
  * @flags: flags for which service functionality to ensure is initialized
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1186,7 +1186,7 @@ secret_service_open_finish (GAsyncResult *result,
  * @service_gtype: the GType of the new secret service
  * @service_bus_name: (nullable): the D-Bus service name of the secret service
  * @flags: flags for which service functionality to ensure is initialized
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Create a new #SecretService proxy for the Secret Service.
@@ -1425,7 +1425,7 @@ secret_service_get_session_dbus_path (SecretService *self)
 /**
  * secret_service_ensure_session:
  * @self: the secret service
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1498,7 +1498,7 @@ secret_service_ensure_session_finish (SecretService *self,
 /**
  * secret_service_ensure_session_sync:
  * @self: the secret service
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Ensure that the #SecretService proxy has established a session with the
@@ -1638,7 +1638,7 @@ on_ensure_collection (GObject *source,
 /**
  * secret_service_load_collections:
  * @self: the secret service
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *
@@ -1736,7 +1736,7 @@ secret_service_load_collections_finish (SecretService *self,
 /**
  * secret_service_load_collections_sync:
  * @self: the secret service
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @error: location to place an error on failure
  *
  * Ensure that the #SecretService proxy has loaded all the collections present
@@ -1803,7 +1803,7 @@ secret_service_load_collections_sync (SecretService *self,
  * secret_service_prompt_sync:
  * @self: the secret service
  * @prompt: the prompt
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @return_type: the variant type of the prompt result
  * @error: location to place an error on failure
  *
@@ -1849,7 +1849,7 @@ secret_service_prompt_sync (SecretService *self,
  * @self: the secret service
  * @prompt: the prompt
  * @return_type: (nullable): the variant type of the prompt result
- * @cancellable: optional cancellation object
+ * @cancellable: (nullable): optional cancellation object
  * @callback: called when the operation completes
  * @user_data: data to be passed to the callback
  *