diff --git a/__init__.py b/__init__.py
index 413b753..bd0d093 100644
--- a/__init__.py
+++ b/__init__.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 from calibre.customize import InterfaceActionBase
 
-VERSION = (3, 7, 1)
+VERSION = (3, 7, 2)
 
 
 class WordDumbDumb(InterfaceActionBase):
diff --git a/metadata.py b/metadata.py
index ba3bd92..5a391e6 100644
--- a/metadata.py
+++ b/metadata.py
@@ -62,9 +62,9 @@ def get_asin(book_path, book_fmt):
     else:
         with open(book_path, 'rb') as f:
             mu = MetadataUpdater(f)
-            if (asin := mu.original_exth_records.get(113, None)) is None:
-                asin = mu.original_exth_records.get(504, None)
-            return asin.decode('utf-8')
+            if (asin := mu.original_exth_records.get(113)) is None:
+                asin = mu.original_exth_records.get(504)
+            return asin.decode('utf-8') if asin else None
     return None