diff --git a/mwparserfromhell/nodes/tag.py b/mwparserfromhell/nodes/tag.py
index e9531e7..e3c7260 100644
--- a/mwparserfromhell/nodes/tag.py
+++ b/mwparserfromhell/nodes/tag.py
@@ -223,7 +223,7 @@ class Tag(Node):
     def wiki_markup(self, value):
         self._wiki_markup = str(value) if value else None
         if not value or not self.closing_wiki_markup:
-            self.closing_wiki_markup = str(value) if value else None
+            self._closing_wiki_markup = self._wiki_markup
 
     @self_closing.setter
     def self_closing(self, value):
diff --git a/tests/test_tag.py b/tests/test_tag.py
index b33b0c2..3beea98 100644
--- a/tests/test_tag.py
+++ b/tests/test_tag.py
@@ -246,6 +246,9 @@ class TestTag(TreeEqualityTestCase):
         node.closing_wiki_markup = "|}"
         self.assertEqual("|}", node.closing_wiki_markup)
         self.assertEqual("{|\n|}", node)
+        node.wiki_markup = "!!"
+        self.assertEqual("|}", node.closing_wiki_markup)
+        self.assertEqual("!!\n|}", node)
         node.wiki_markup = False
         self.assertFalse(node.closing_wiki_markup)
         self.assertEqual("<table>\n</table>", node)