diff --git a/modules/reitit-core/src/reitit/middleware.cljc b/modules/reitit-core/src/reitit/middleware.cljc
index d135843b..591a9c97 100644
--- a/modules/reitit-core/src/reitit/middleware.cljc
+++ b/modules/reitit-core/src/reitit/middleware.cljc
@@ -6,7 +6,7 @@
 (defprotocol IntoMiddleware
   (into-middleware [this data opts]))
 
-(defrecord Middleware [name wrap])
+(defrecord Middleware [name wrap spec])
 (defrecord Endpoint [data handler middleware])
 
 (def ^:dynamic *max-compile-depth* 10)
diff --git a/modules/reitit-ring/src/reitit/ring/spec.cljc b/modules/reitit-ring/src/reitit/ring/spec.cljc
index 96c407fa..3f8c6020 100644
--- a/modules/reitit-ring/src/reitit/ring/spec.cljc
+++ b/modules/reitit-ring/src/reitit/ring/spec.cljc
@@ -1,15 +1,13 @@
 (ns reitit.ring.spec
   (:require [clojure.spec.alpha :as s]
-            [reitit.middleware #?@(:cljs [:refer [Middleware]])]
-            [reitit.spec :as rs])
-  #?(:clj
-     (:import (reitit.middleware Middleware))))
+            [reitit.middleware :as middleware]
+            [reitit.spec :as rs]))
 
 ;;
 ;; Specs
 ;;
 
-(s/def ::middleware (s/coll-of (partial instance? Middleware)))
+(s/def ::middleware (s/coll-of (partial satisfies? middleware/IntoMiddleware)))
 
 (s/def ::data
   (s/keys :req-un [::rs/handler]
@@ -19,10 +17,22 @@
 ;; Validator
 ;;
 
+(defn merge-specs [specs]
+  (when-let [non-specs (seq (remove #(or (s/spec? %) (s/get-spec %)) specs))]
+    (throw
+      (ex-info
+        (str "Not all specs satisfy the Spec protocol: " non-specs)
+        {:specs specs
+         :non-specs non-specs})))
+  (s/merge-spec-impl (vec specs) (vec specs) nil))
+
 (defn- validate-ring-route-data [routes spec]
   (->> (for [[p _ c] routes
-             [method {:keys [data] :as endpoint}] c
-             :when endpoint]
+             [method {:keys [data middleware] :as endpoint}] c
+             :when endpoint
+             :let [mw-specs (seq (keep :spec middleware))
+                   specs (keep identity (into [spec] mw-specs))
+                   spec (merge-specs specs)]]
          (when-let [problems (and spec (s/explain-data spec data))]
            (rs/->Problem p method data spec problems)))
        (keep identity) (seq)))
diff --git a/test/cljc/reitit/ring_spec_test.cljc b/test/cljc/reitit/ring_spec_test.cljc
index 8d063d79..726d8e0e 100644
--- a/test/cljc/reitit/ring_spec_test.cljc
+++ b/test/cljc/reitit/ring_spec_test.cljc
@@ -2,11 +2,14 @@
   (:require [clojure.test :refer [deftest testing is]]
             [reitit.ring :as ring]
             [reitit.ring.spec :as rrs]
+            [clojure.spec.alpha :as s]
             [reitit.core :as r]
-            [reitit.spec :as rs])
+            [expound.alpha :as e])
   #?(:clj
      (:import (clojure.lang ExceptionInfo))))
 
+(s/def ::role #{:admin :user})
+(s/def ::roles (s/and (s/coll-of ::role :into #{}) set?))
 
 (deftest route-data-validation-test
   (testing "validation is turned off by default"
@@ -27,13 +30,6 @@
           (ring/router
             ["/api" {:handler identity
                      :name "kikka"}]
-            {:validate rrs/validate-spec!})))
-    (is (thrown-with-msg?
-          ExceptionInfo
-          #"Invalid route data"
-          (ring/router
-            ["/api" {:handler identity
-                     :middleware [{}]}]
             {:validate rrs/validate-spec!}))))
 
   (testing "all endpoints are validated"
@@ -48,5 +44,36 @@
     (is (true? (r/router?
                  (ring/router
                    ["/api" {:handler "identity"}]
-                   {:spec any?
-                    :validate rrs/validate-spec!}))))))
+                   {:spec (s/spec any?)
+                    :validate rrs/validate-spec!}))))
+
+    (testing "predicates are not allowed"
+      (is (thrown-with-msg?
+            ExceptionInfo
+            #"Not all specs satisfy the Spec protocol"
+            (ring/router
+              ["/api" {:handler "identity"}]
+              {:spec any?
+               :validate rrs/validate-spec!})))))
+
+  (testing "middleware can contribute to specs"
+    (is (true? (r/router?
+                 (ring/router
+                   ["/api" {:get {:handler identity
+                                  :roles #{:admin}}}]
+                   {:validate rrs/validate-spec!
+                    :data {:middleware [{:spec (s/keys :opt-un [::roles])
+                                         :wrap (fn [handler]
+                                                 (fn [request]
+                                                   (handler request)))}]}}))))
+    (is (thrown-with-msg?
+          ExceptionInfo
+          #"Invalid route data"
+          (ring/router
+            ["/api" {:get {:handler identity
+                           :roles #{:adminz}}}]
+            {:validate rrs/validate-spec!
+             :data {:middleware [{:spec (s/keys :opt-un [::roles])
+                                  :wrap (fn [handler]
+                                          (fn [request]
+                                            (handler request)))}]}})))))