diff --git a/src/mte.ml b/src/mte.ml
index 49d5cdd4..483e14ae 100644
--- a/src/mte.ml
+++ b/src/mte.ml
@@ -15,27 +15,32 @@ type response = {
   content: string;
 }
 
+let request_route request =
+  match String.split_on_char '/' request.target with
+  | "" :: l -> l
+  | _ -> assert false
+
+let content_type_to_string = function
+  | `Text_plain -> "text/plain"
+  | `Application_json -> "application/json"
+
+let default_headers ~content typ =
+  Headers.of_list
+    [
+      ("content-length", string_of_int (String.length content));
+      ("connection", "close"); ("content-type", content_type_to_string typ);
+    ]
+
 let home_page_text =
   "Hello!\n\nThis is MTE, the MirageOS Taler Exchange unikernel."
 
 let request_handler request =
-  match String.split_on_char '/' request.target with
-  | [ ""; "" ] ->
-      let headers =
-        Headers.of_list
-          [
-            ("content-length", string_of_int (String.length home_page_text));
-            ("connection", "close"); ("content-type", "text/plain");
-          ]
-      in
-      { status= `OK; headers; content= home_page_text }
+  match request_route request with
+  | [ "" ] ->
+      let content = home_page_text in
+      let headers = default_headers ~content `Text_plain in
+      { status= `OK; headers; content }
   | _ ->
       let content = "Not found." in
-      let headers =
-        Headers.of_list
-          [
-            ("content-length", string_of_int (String.length content));
-            ("connection", "close"); ("content-type", "text/plain");
-          ]
-      in
+      let headers = default_headers ~content `Text_plain in
       { status= `Not_found; headers; content }