diff --git a/redstring/library.py b/redstring/library.py
index 6982937..0579b6c 100644
--- a/redstring/library.py
+++ b/redstring/library.py
@@ -17,16 +17,18 @@ def generate_index_document(directory: str) -> Document:
             document: Document = load(f)
 
         # Check if this document specifies a tab, and create it if necessary.
-        category = document.get_tag('category')
-        if not category:
+        if category_tag := document.get_tag('category'):
+            category = category_tag.value
+        else:
             category = 'index'
         if category not in categories:
             categories[category] = {}
         category_tab = categories[category]
 
         # Check if this document specifies a topic, and create it if necessary.
-        topic = document.get_tag('topic')
-        if not topic:
+        if topic_tag := document.get_tag('topic'):
+            topic = topic_tag.value
+        else:
             topic = 'uncategorized'
         if '.' in topic:
             topic, subtopic = topic.split('.', maxsplit=1)