diff --git a/README.md b/README.md
index 91cb321..331694f 100644
--- a/README.md
+++ b/README.md
@@ -44,7 +44,7 @@ addItem : String -> Task (HttpExtra.Error String) (HttpExtra.Response (List Stri
 addItem item =
   HttpExtra.post "http://example.com/api/items"
     |> withBody (Http.string "{ \"item\": \"" ++ item ++ "\" }")
-    |> withHeader ("Content-Type", "application/json")
+    |> withHeader "Content-Type" "application/json"
     |> withTimeout (10 * Time.second)
     |> withCredentials
     |> send (jsonReader itemsDecoder) stringReader
diff --git a/src/Http/Extra.elm b/src/Http/Extra.elm
index 37baa36..ef22fcb 100644
--- a/src/Http/Extra.elm
+++ b/src/Http/Extra.elm
@@ -143,9 +143,9 @@ delete =
     get "https://example.com/api/items/1"
       |> withHeader ("Content-Type", "application/json")
 -}
-withHeader : (String, String) -> RequestBuilder -> RequestBuilder
-withHeader header =
-  mapRequest <| \request -> { request | headers = header :: request.headers }
+withHeader : String -> String -> RequestBuilder -> RequestBuilder
+withHeader key value =
+  mapRequest <| \request -> { request | headers = (key, value) :: request.headers }
 
 
 {-| Add many headers to a request