diff --git a/content/v2.0/query-data/guides/custom-functions/custom-aggregate.md b/content/v2.0/query-data/guides/custom-functions/custom-aggregate.md
index 10d6214d1..578df7946 100644
--- a/content/v2.0/query-data/guides/custom-functions/custom-aggregate.md
+++ b/content/v2.0/query-data/guides/custom-functions/custom-aggregate.md
@@ -18,7 +18,7 @@ or create custom aggregate functions using the
 Aggregate functions all have the same basic characteristics:
 
 - They operate on individual input tables and transform all records into a single record.
-- The output table has the same group key as the input table.
+- The output table has the same [group key](/v2.0/query-data/get-started/#group-keys) as the input table.
 
 ## How reduce() works
 The `reduce()` function operates on one row at a time using the function defined in