diff --git a/liara/nodes.py b/liara/nodes.py
index 1611137..b5a4d1d 100644
--- a/liara/nodes.py
+++ b/liara/nodes.py
@@ -421,7 +421,6 @@ class MarkdownDocumentNode(DocumentNode):
     def __init__(self, configuration, **kwargs):
         super().__init__(**kwargs)
         self.__md = self._create_markdown_processor(configuration)
-        self.__mdext = None
 
     def _create_markdown_processor(self, configuration):
         from markdown import Markdown
@@ -445,7 +444,6 @@ def process(self, cache: Cache, **kwargs):
         from .md import ShortcodeException
 
         if '$data' in kwargs:
-            assert self.__mdext
             self.__mdext.set_data(kwargs['$data'])
 
         byte_content = self._raw_content.encode('utf-8')
diff --git a/test/test_shortcode.py b/test/test_shortcode.py
new file mode 100644
index 0000000..11935bb
--- /dev/null
+++ b/test/test_shortcode.py
@@ -0,0 +1,44 @@
+from liara import cmdline
+from liara.signals import register_markdown_shortcodes
+import liara
+from click.testing import CliRunner
+
+_TEST_DATA = {}
+
+
+def test_shortcode_with_data(tmp_path):
+    global _TEST_DATA
+    runner = CliRunner()
+    with runner.isolated_filesystem(temp_dir=tmp_path):
+        result = runner.invoke(cmdline.cli, ['quickstart'])
+        assert result.exit_code == 0
+
+        # Add a data file to content
+        data = {
+            'root': 'some data'
+        }
+
+        open('content/_index.md', 'w').write("""
+---
+title: Hello world
+---
+
+Invoke a shortcode: <% test /%>""")
+
+        liara.yaml.dump_yaml(data, open('content/_data.yaml', 'w'))
+
+        register_markdown_shortcodes.connect(_register_test_shortcode)
+
+        s = liara.Liara()
+        s.build()
+
+        assert _TEST_DATA['root'] == 'some data'
+
+
+def _test_shortcode(**kwargs):
+    global _TEST_DATA
+    _TEST_DATA = kwargs['$data']
+
+
+def _register_test_shortcode(sender, preprocessor):
+    preprocessor.register('test', _test_shortcode)