diff --git a/api.ipynb b/api.ipynb
index 74a9d3f..b77159c 100644
--- a/api.ipynb
+++ b/api.ipynb
@@ -336,6 +336,8 @@
     "            property_value['@id'] = f'{self.api_url}/items/{value[\"value\"]}'\n",
     "            property_value['value_resource_id'] = value['value']\n",
     "            property_value['value_resource_name'] = 'items'\n",
+    "        elif data_type == 'numeric:timestamp':\n",
+    "            property_value['@value'] = value['value']\n",
     "        elif data_type == 'uri':\n",
     "            property_value['@id'] = value['value']\n",
     "        else:\n",
diff --git a/omeka_s_tools/api.py b/omeka_s_tools/api.py
index bb56cbe..5b09bfa 100644
--- a/omeka_s_tools/api.py
+++ b/omeka_s_tools/api.py
@@ -298,6 +298,8 @@ def prepare_property_value(self, value, property_id):
             property_value['@id'] = f'{self.api_url}/items/{value["value"]}'
             property_value['value_resource_id'] = value['value']
             property_value['value_resource_name'] = 'items'
+        elif data_type == 'numeric:timestamp':
+            property_value['@value'] = value['value']
         elif data_type == 'uri':
             property_value['@id'] = value['value']
         else: