diff --git a/src/calibre/ebooks/metadata/amazon.py b/src/calibre/ebooks/metadata/amazon.py
index 98a2ac6d36..58dd3f1d22 100644
--- a/src/calibre/ebooks/metadata/amazon.py
+++ b/src/calibre/ebooks/metadata/amazon.py
@@ -50,7 +50,7 @@ def to_asin(br, isbn):
     else:
         asin = isbn
     with cache_lock:
-        asin_cache[isbn] = ans if ans else False
+        asin_cache[isbn] = asin if asin else False
     return asin