diff --git a/CHANGELOG.md b/CHANGELOG.md
index 727abb8..147bca4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## 0.4.2
+
+- Join path with baseurl using a `/` where necessary
+- Allow to specify the Content-Type and Authorization request headers manually
+
 ## 0.4.1
 
 - Include httpkit error in exception when available
diff --git a/project.clj b/project.clj
index ede7ed1..c24c9a5 100644
--- a/project.clj
+++ b/project.clj
@@ -1,4 +1,4 @@
-(defproject dev.nubank/clj-github "0.4.1"
+(defproject dev.nubank/clj-github "0.4.2"
   :description "A Clojure library for interacting with the github developer API"
   :url "https://github.com/nubank/clj-github"
   :license {:name "EPL-2.0 OR GPL-2.0-or-later WITH Classpath-exception-2.0"
diff --git a/src/clj_github/httpkit_client.clj b/src/clj_github/httpkit_client.clj
index 64de116..10c0e22 100644
--- a/src/clj_github/httpkit_client.clj
+++ b/src/clj_github/httpkit_client.clj
@@ -11,14 +11,20 @@
 (defn get-installation-token [{:keys [token-fn]}]
   (token-fn))
 
+(defn- append-url-path [baseurl path]
+  (str baseurl (when-not (or (.endsWith baseurl "/")
+                             (.startsWith path "/"))
+                 "/") path))
+
 (defn- prepare
-  [{:keys [token-fn]} {:keys [path method body] :or {method :get} :as request}]
+  [{:keys [token-fn]} {:keys [path method body] :or {method :get path ""} :as request}]
   (-> request
       (assoc :method method)
       (assoc-some :body (and body (cheshire/generate-string body)))
-      (assoc :url (str github-url path))
-      (assoc-in [:headers "Content-Type"] "application/json")
-      (assoc-in [:headers "Authorization"] (str "Bearer " (token-fn)))))
+      (assoc :url (append-url-path github-url path))
+      ;; TODO http headers are case insensitive, also this could be keywords
+      (update-in [:headers "Content-Type"] #(or % "application/json"))
+      (update-in [:headers "Authorization"] #(or % (str "Bearer " (token-fn))))))
 
 (defn- parse-body [content-type body]
   (if (and content-type (re-find #"application/json" content-type))
@@ -30,14 +36,16 @@
       (get-in response [:headers "Content-Type"])))
 
 (defn request [client req-map]
-  (let [response @(httpkit/request (prepare client req-map))]
+  (let [request (prepare client req-map)
+        response @(httpkit/request request)]
     (if (success-codes (:status response))
       (update response :body (partial parse-body (content-type response)))
       (throw (ex-info "Request to GitHub failed"
                       {:response (select-keys response [:status :body])}
                       (:error response))))))
 
-(defn new-client [{:keys [app-id private-key token org] :as opts}]
+(defn new-client [{:keys [app-id private-key token org token-fn] :as opts}]
+  {:pre [(or token app-id token-fn)]}
   (cond
     token
     {:token-fn (constantly token)}
diff --git a/test/clj_github/httpkit_client_test.clj b/test/clj_github/httpkit_client_test.clj
index 7733f17..6ccbb1f 100644
--- a/test/clj_github/httpkit_client_test.clj
+++ b/test/clj_github/httpkit_client_test.clj
@@ -24,6 +24,10 @@
       (with-fake-http [{:url "https://api.github.com/path"}
                        {:status 200}]
         (is (match? {:status 200} (sut/request client {:path "/path"})))))
+    (testing "path is appended to url with optional slash"
+      (with-fake-http [{:url "https://api.github.com/path"}
+                       {:status 200}]
+        (is (match? {:status 200} (sut/request client {:path "path"})))))
     (testing "github token is added to authorization header"
       (with-fake-http [{:headers {"Authorization" "Bearer token"
                                   "Content-Type" "application/json"}}
@@ -43,4 +47,28 @@
         (with-fake-http [{} {:error cause :status nil}]
           (let [e (try (sut/request client {}) (catch Exception e e))]
             (is (re-matches #"(?i)Request to GitHub failed" (.getMessage e)))
-            (is (= cause (.getCause e)))))))))
+            (is (= cause (.getCause e)))))))
+    (testing "request headers"
+      (testing "Can use custom headers"
+        (with-fake-http [(fn [req]
+                           (is (= "test" (get-in req [:headers "Test-Header"]))))
+                         {:status 200}]
+          ;; assertion is in fake http callback
+          (sut/request client {:headers {"Test-Header" "test"}})))
+      (testing "Can override authentication"
+        ;; clj-github sets authorization header unless specified. Beware that the
+        ;; implementation here is case sensitive whereas HTTP headers are not.
+        (with-fake-http [(fn [req]
+                           (is (= "Test SomeValue" (get-in req [:headers "Authorization"]))))
+                         {:status 200}]
+          ;; assertion is in fake http callback
+          (sut/request client {:headers {"Authorization" "Test SomeValue"}})))
+      (testing "Can override content-type"
+        ;; clj-github sets the content-type header unless specified. Beware that the
+        ;; implementation here is case sensitive whereas HTTP headers are not.
+        (with-fake-http [(fn [req]
+                           (is (= "test/test" (get-in req [:headers "Content-Type"]))))
+                         {:status 200}]
+          ;; assertion is in fake http callback
+          (sut/request client {:headers {"Content-Type" "test/test"}}))))))
+