diff --git a/README.md b/README.md
index fba038b..50727aa 100644
--- a/README.md
+++ b/README.md
@@ -83,7 +83,9 @@ You can set all  the following variables:
 * `PLANTUML_STATS`
     * Set it to `on` to enable [statistics report](http://plantuml.com/statistics-report)
     * Default value `off`
-
+* `HTTP_AUTHORIZATION`
+    * when calling the `proxy` endpoint, the value of `HTTP_AUTHORIZATION` will be used to set the HTTP Authorization header
+    * Default value: null
 
 
 Alternate: How to build your docker image
diff --git a/src/main/java/net/sourceforge/plantuml/servlet/ProxyServlet.java b/src/main/java/net/sourceforge/plantuml/servlet/ProxyServlet.java
index c124122..979abde 100644
--- a/src/main/java/net/sourceforge/plantuml/servlet/ProxyServlet.java
+++ b/src/main/java/net/sourceforge/plantuml/servlet/ProxyServlet.java
@@ -135,20 +135,18 @@ public class ProxyServlet extends HttpServlet {
     }
 
     private HttpURLConnection getConnection(final URL url) throws IOException {
-        if (url.getProtocol().startsWith("https")) {
-            HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
-            con.setRequestMethod("GET");
-            con.setReadTimeout(10000); // 10 seconds
-            // printHttpsCert(con);
-            con.connect();
-            return con;
-        } else {
-            HttpURLConnection con = (HttpURLConnection) url.openConnection();
-            con.setRequestMethod("GET");
-            con.setReadTimeout(10000); // 10 seconds
-            con.connect();
-            return con;
+        final HttpURLConnection con = (HttpURLConnection) url.openConnection();
+        if (con instanceof HttpsURLConnection) {
+            // printHttpsCert((HttpsURLConnection) con);
         }
+        con.setRequestMethod("GET");
+        String token = System.getenv("HTTP_AUTHORIZATION");
+        if (token != null) {
+            con.setRequestProperty("Authorization", token);
+        }
+        con.setReadTimeout(10000); // 10 seconds
+        con.connect();
+        return con;
     }
 
     /**