diff --git a/Definition-format.md b/Definition-format.md
index d7b1678..aa830ed 100644
--- a/Definition-format.md
+++ b/Definition-format.md
@@ -747,7 +747,7 @@ search:
     # You give them a name and use them to extract additional data from the row sets, which you can use in
     # conditionals for setting strings for other fields, or as direct values for concatenating into strings. 
     #
-    # [OPTIONAL] tracker category id (id field from caps/categorymappings)
+    # [REQUIRED] tracker category id (id field from caps/categorymappings)
     # While not required, it is usual to return a category for Torznab apps to use,
     # so if the site does not provide one in its results, then use category Other.     
     category: