diff --git a/README.md b/README.md
index ff89d226..84cc2dfd 100644
--- a/README.md
+++ b/README.md
@@ -609,7 +609,96 @@ The `:gen` -version has 50% less code, is easier to reason about and is 2-4x fas
 
 *TODO*
 
-## Validating meta-data
+## Validating route-trees
+
+Namespace `reitit.spec` contains [specs](https://clojure.org/about/spec) for routes, router and router options.
+
+To enable spec-validation of `router` inputs & outputs at development time, one can do the following:
+
+```clj
+; add to dependencies:
+; [expound "0.3.0"]
+
+(require '[clojure.spec.test.alpha :as st])
+(require '[expound.alpha :as expound])
+(require '[clojure.spec.alpha :as s])
+(require '[reitit.spec])
+
+(st/instrument `reitit/router)
+(set! s/*explain-out* expound/printer)
+
+(reitit/router
+  ["/api"
+   ["/publuc"
+    ["/ping"]
+    ["pong"]]])
+; -- Spec failed --------------------
+;
+; ["/api" ...]
+;  ^^^^^^
+;
+;     should satisfy
+;
+; (clojure.spec.alpha/cat
+;   :path
+;   :reitit.spec/path
+;   :arg
+;   (clojure.spec.alpha/? :reitit.spec/arg)
+;   :childs
+;   (clojure.spec.alpha/* (clojure.spec.alpha/and :reitit.spec/raw-route)))
+;
+; -- Relevant specs -------
+;
+; :reitit.spec/raw-route:
+; (clojure.spec.alpha/cat
+;   :path
+;   :reitit.spec/path
+;   :arg
+;   (clojure.spec.alpha/? :reitit.spec/arg)
+;   :childs
+;   (clojure.spec.alpha/* (clojure.spec.alpha/and :reitit.spec/raw-route)))
+; :reitit.spec/raw-routes:
+; (clojure.spec.alpha/or
+;   :route
+;   :reitit.spec/raw-route
+;   :routes
+;   (clojure.spec.alpha/coll-of :reitit.spec/raw-route :into []))
+;
+; -- Spec failed --------------------
+;
+; [... [... ... ["pong"]]]
+;                ^^^^^^
+;
+;     should satisfy
+;
+; (fn [%] (clojure.string/starts-with? % "/"))
+;
+; -- Relevant specs -------
+;
+; :reitit.spec/path:
+; (clojure.spec.alpha/and
+;   clojure.core/string?
+;   (clojure.core/fn [%] (clojure.string/starts-with? % "/")))
+; :reitit.spec/raw-route:
+; (clojure.spec.alpha/cat
+;   :path
+;   :reitit.spec/path
+;   :arg
+;   (clojure.spec.alpha/? :reitit.spec/arg)
+;   :childs
+;   (clojure.spec.alpha/* (clojure.spec.alpha/and :reitit.spec/raw-route)))
+; :reitit.spec/raw-routes:
+; (clojure.spec.alpha/or
+;   :route
+;   :reitit.spec/raw-route
+;   :routes
+;   (clojure.spec.alpha/coll-of :reitit.spec/raw-route :into []))
+;
+; -------------------------
+; Detected 2 errors
+```
+
+### Validating meta-data
 
 *TODO*
 
diff --git a/project.clj b/project.clj
index f843d35e..378b9e39 100644
--- a/project.clj
+++ b/project.clj
@@ -26,7 +26,7 @@
                                   [metosin/spec-tools "0.3.3"]
                                   [org.clojure/spec.alpha "0.1.123"]
 
-                                  [expound "0.2.1"]
+                                  [expound "0.3.0"]
                                   [orchestra "2017.08.13"]
 
                                   [criterium "0.4.4"]
diff --git a/src/reitit/coercion.cljc b/src/reitit/coercion.cljc
index 4879f50a..ea404b27 100644
--- a/src/reitit/coercion.cljc
+++ b/src/reitit/coercion.cljc
@@ -194,4 +194,3 @@
                      (coerce-response coercers request (handler request)))
                     ([request respond raise]
                      (handler request #(respond (coerce-response coercers request %)) raise)))))))}))
-