diff --git a/src/honeysql/format.clj b/src/honeysql/format.clj
index 9d09f0d..a523176 100644
--- a/src/honeysql/format.clj
+++ b/src/honeysql/format.clj
@@ -393,7 +393,7 @@
 (defmethod format-clause :over [[_ part-clause] _]
   (str "OVER " (to-sql part-clause)))
 
-(defmethod format-clause :aggregate [[_ [aggregate-fn _]] _]
+(defmethod format-clause :aggregate [[_ aggregate-fn] _]
   (str (to-sql aggregate-fn)))
 
 (defmethod format-clause :partition-by [[_ fields] _]
diff --git a/src/honeysql/helpers.clj b/src/honeysql/helpers.clj
index ba4fa9d..e2fc39c 100644
--- a/src/honeysql/helpers.clj
+++ b/src/honeysql/helpers.clj
@@ -228,7 +228,7 @@
            (update-in m [:over] (partial apply merge) (collify fields)))
 
 (defhelper aggregate [m aggregate-fn]
-           (assoc m :aggregate aggregate-fn))
+           (assoc m :aggregate (first aggregate-fn)))
 
 (defhelper spartition-by [m fields]
            (assoc m :partition-by (collify fields)))