diff --git a/src/cemerick/url.cljx b/src/cemerick/url.cljx
index 75ff53d..3a4915a 100644
--- a/src/cemerick/url.cljx
+++ b/src/cemerick/url.cljx
@@ -5,14 +5,17 @@
             [clojure.string :as string]
             #+cljs [goog.Uri :as uri]))
 
+(defmulti url-encode
+  (fn ([_ encoding] encoding)))
+
 #+clj
-(defn url-encode
-  [string]
+(defmethod url-encode :default
+  [string _]
   (some-> string str (URLEncoder/encode "UTF-8") (.replace "+" "%20")))
 
 #+cljs
-(defn url-encode
-  [string]
+(defmethod url-encode :default
+  [string _]
   (some-> string str (js/encodeURIComponent) (.replace "+" "%20")))
 
 #+clj
@@ -27,16 +30,18 @@
   (some-> string str (js/decodeURIComponent)))
 
 (defn map->query
-  [m]
-  (some->> (seq m)
-    sort                     ; sorting makes testing a lot easier :-)
-    (map (fn [[k v]]
-           [(url-encode (name k))
-            "="
-            (url-encode (str v))]))
-    (interpose "&")
-    flatten
-    (apply str)))
+  ([m]
+   (map->query m nil))
+  ([m encoding]
+   (some->> (seq m)
+            sort; sorting makes testing a lot easier :-)
+            (map (fn [[k v]]
+                   [(url-encode (name k) encoding)
+                    "="
+                    (url-encode (str v) encoding)]))
+            (interpose "&")
+            flatten
+            (apply str))))
 
 (defn split-param [param]
   (->
diff --git a/test/cemerick/test_url.cljx b/test/cemerick/test_url.cljx
index fe2e6d1..07a5c00 100644
--- a/test/cemerick/test_url.cljx
+++ b/test/cemerick/test_url.cljx
@@ -15,6 +15,14 @@
        "a=1&b=2" {"a" "1" "b" "2"}
        "a=" {"a" ""}))
 
+(defmethod url-encode :append-foobar
+  [string _]
+  (str string "foobar"))
+
+(deftest test-map-to-query-str-extention
+  (is (= "afoobar=custom-encodingfoobar"
+      (map->query {:a "custom-encoding"} :append-foobar))))
+
 (deftest url-roundtripping
   (let [aurl (url "https://username:password@some.host.com/database?query=string")]
     (is (= "https://username:password@some.host.com/database?query=string" (str aurl)))