diff --git a/lib/core/md_yaml_doc_codec.dart b/lib/core/md_yaml_doc_codec.dart
index 22bb31cc..05a3549e 100644
--- a/lib/core/md_yaml_doc_codec.dart
+++ b/lib/core/md_yaml_doc_codec.dart
@@ -91,9 +91,7 @@ class MarkdownYAMLCodec {
       if (yamlMap is! Map) {
         return map;
       }
-      yamlMap.forEach((key, value) {
-        map[key] = value;
-      });
+      map = _convertMap(yamlMap);
     } catch (err) {
       Log.d('MarkdownYAMLSerializer::decode("$yamlText") -> ${err.toString()}');
     }
@@ -125,3 +123,16 @@ class MarkdownYAMLCodec {
     return "---\n" + yaml + "---\n";
   }
 }
+
+LinkedHashMap<String, dynamic> _convertMap(YamlMap yamlMap) {
+  LinkedHashMap<String, dynamic> map = LinkedHashMap<String, dynamic>();
+
+  yamlMap.forEach((key, value) {
+    if (value is YamlMap) {
+      value = _convertMap(value);
+    }
+    map[key] = value;
+  });
+
+  return map;
+}
diff --git a/test/md_yaml_codec_test.dart b/test/md_yaml_codec_test.dart
index d01d321b..1b750094 100644
--- a/test/md_yaml_codec_test.dart
+++ b/test/md_yaml_codec_test.dart
@@ -1,6 +1,7 @@
 import 'dart:collection';
 
 import 'package:test/test.dart';
+import 'package:yaml/yaml.dart';
 
 import 'package:gitjournal/core/md_yaml_doc.dart';
 import 'package:gitjournal/core/md_yaml_doc_codec.dart';
@@ -208,5 +209,24 @@ foo: bar
     // FIXME: Add another test for yaml header at the bottom without a newline
     // FIXME: Add another test for yaml header at the bottom with lots of new lines after
     // FIXME: Add another test for yaml header at the bottom with lots of new lines with spaces after
+
+    test('Should not have any YamlMaps', () {
+      // YamlMaps cannot be sent over an isolate
+
+      var str = """---
+thumbnail: {
+  name: "adrian_sommeling.jpg",
+  alt: "Padre e hijo se cubren con un paraguas de una tormenta que hace volar al niño",
+  style: top
+}
+tags: ["opinión", "autores"]
+---
+""";
+
+      var serializer = MarkdownYAMLCodec();
+      var doc = serializer.decode(str);
+
+      expect(doc.props['thumbnail'].runtimeType, isNot(YamlMap));
+    });
   });
 }