(reitit.coercion.malli/-get-apidocs-openapi
   (reitit.coercion.malli/create)
   {:parameters {:query [:and {:registry {::foo string?}}
                         [:map [:x :int] [:y :int] [:foo ::foo]]
                         [:fn (fn [{:keys [x y]}]
                                (< x y))]]}}
   nil)

diff --git a/modules/reitit-malli/src/reitit/coercion/malli.cljc b/modules/reitit-malli/src/reitit/coercion/malli.cljc
index 6f4dff5b..1b1b5860 100644
--- a/modules/reitit-malli/src/reitit/coercion/malli.cljc
+++ b/modules/reitit-malli/src/reitit/coercion/malli.cljc
@@ -136,10 +136,16 @@
 (defn -get-apidocs-openapi
   [coercion {:keys [parameters responses content-types] :or {content-types ["application/json"]}} options]
   (let [{:keys [body request multipart]} parameters
+        definitions (volatile! {})
         parameters (dissoc parameters :request :body :multipart)
         ->schema-object (fn [schema opts]
-                          (let [current-opts (merge options opts)]
-                            (json-schema/transform schema current-opts)))]
+                          (let [current-opts (merge options opts)
+                                ret (json-schema/transform schema current-opts)]
+                            (vswap! definitions merge (:definitions ret))
+                            ;; hack for :and schema
+                            (if (contains? ret :allOf)
+                              (-> ret :allOf first)
+                              ret)))]
     (merge
      (when (seq parameters)
        {:parameters
@@ -216,7 +222,10 @@
                        [status (merge (select-keys response [:description])
                                       (when content
                                         {:content content}))])))
-              responses)}))))
+              responses)})
+
+     (when (seq @definitions)
+       {:definitions @definitions}))))

 (defn create
   ([]