diff --git a/src/main/java/com/smartystreets/api/Request.java b/src/main/java/com/smartystreets/api/Request.java
index 435f69e..1331244 100644
--- a/src/main/java/com/smartystreets/api/Request.java
+++ b/src/main/java/com/smartystreets/api/Request.java
@@ -47,6 +47,8 @@ private static String urlEncode(String value) {
     public String getUrl() {
         String url = this.urlPrefix;
 
+        this.headers.put("content-type", this.contentType);
+
         if (!url.contains("?"))
             url += "?";