diff --git a/resources/clj-kondo.exports/de.active-group/active-clojure/config.edn b/resources/clj-kondo.exports/de.active-group/active-clojure/config.edn
index 8e2ea5e..f914e47 100644
--- a/resources/clj-kondo.exports/de.active-group/active-clojure/config.edn
+++ b/resources/clj-kondo.exports/de.active-group/active-clojure/config.edn
@@ -2,5 +2,6 @@
  :hooks {:analyze-call {active.clojure.monad/monadic hooks.monad/monadic
                         active.clojure.cljs.record/define-record-type hooks.record/define-record-type
                         active.clojure.cljs.record/define-singleton-type hooks.record/define-singleton-type
+                        active.clojure.sum-type/define-sum-type hooks.sum-type/define-sum-type
                         active.clojure.record/define-record-type hooks.record/define-record-type
                         active.clojure.record/define-singleton-type hooks.record/define-singleton-type}}}
diff --git a/resources/clj-kondo.exports/de.active-group/active-clojure/hooks/sum_type.clj b/resources/clj-kondo.exports/de.active-group/active-clojure/hooks/sum_type.clj
new file mode 100644
index 0000000..287fc76
--- /dev/null
+++ b/resources/clj-kondo.exports/de.active-group/active-clojure/hooks/sum_type.clj
@@ -0,0 +1,13 @@
+(ns hooks.sum-type
+  (:require [clj-kondo.hooks-api :as api]))
+
+(defn define-sum-type
+  [expr]
+  (update expr :node
+          (fn [node]
+            (let [[sum-type-name predicate] (rest (:children node))]
+              (api/list-node
+               (list (api/token-node 'do)
+                     (api/list-node [(api/token-node 'declare) sum-type-name])
+                     (api/list-node [(api/token-node 'declare) predicate])))))))
+