diff --git a/src/main/java/com/smartystreets/api/ClientBuilder.java b/src/main/java/com/smartystreets/api/ClientBuilder.java
index 173d29b..bb6460f 100644
--- a/src/main/java/com/smartystreets/api/ClientBuilder.java
+++ b/src/main/java/com/smartystreets/api/ClientBuilder.java
@@ -17,7 +17,7 @@ public class ClientBuilder {
     private int maxTimeout;
     private String urlPrefix;
     private Proxy proxy;
-    private Map<String, String> customHeaders;
+    private Map<String, Object> customHeaders;
     private final String INTERNATIONAL_STREET_API_URL = "https://international-street.api.smartystreets.com/verify";
     private final String US_AUTOCOMPLETE_API_URL = "https://us-autocomplete.api.smartystreets.com/suggest";
     private final String US_EXTRACT_API_URL = "https://us-extract.api.smartystreets.com/";
@@ -89,10 +89,10 @@ public ClientBuilder withCustomBaseUrl(String baseUrl) {
 
     /**
      * Use this to add any additional headers you need.
-     * @param customHeaders A string to string <b>Map</b> of header name/value pairs.
+     * @param customHeaders A String to Object <b>Map</b> of header name/value pairs.
      * @return Returns <b>this</b> to accommodate method chaining.
      */
-    public ClientBuilder withCustomHeaders(Map<String, String> customHeaders) {
+    public ClientBuilder withCustomHeaders(Map<String, Object> customHeaders) {
         this.customHeaders = customHeaders;
         return this;
     }
diff --git a/src/main/java/com/smartystreets/api/CustomHeaderSender.java b/src/main/java/com/smartystreets/api/CustomHeaderSender.java
index 8f1f4ff..d493c97 100644
--- a/src/main/java/com/smartystreets/api/CustomHeaderSender.java
+++ b/src/main/java/com/smartystreets/api/CustomHeaderSender.java
@@ -6,20 +6,18 @@
 import java.util.Map;
 
 public class CustomHeaderSender implements Sender {
-    private Map<String, String> headers;
+    private Map<String, Object> headers;
     private Sender inner;
 
-    public CustomHeaderSender(Map<String, String> headers, Sender inner){
+    public CustomHeaderSender(Map<String, Object> headers, Sender inner){
         this.headers = headers;
         this.inner = inner;
     }
 
     @Override
     public Response send(Request request) throws SmartyException, IOException {
-        Map<String, String> requestHeaders = request.getHeaders();
-
         for (Map.Entry entry : this.headers.entrySet()) {
-            request.putHeader((String)entry.getKey(), (String)entry.getValue());
+            request.putHeader((String)entry.getKey(), entry.getValue());
         }
 
         return this.inner.send(request);
diff --git a/src/main/java/com/smartystreets/api/GoogleSender.java b/src/main/java/com/smartystreets/api/GoogleSender.java
index 7975d3e..c1722e4 100644
--- a/src/main/java/com/smartystreets/api/GoogleSender.java
+++ b/src/main/java/com/smartystreets/api/GoogleSender.java
@@ -65,7 +65,7 @@ private HttpRequest buildHttpRequest(Request smartyRequest) throws IOException {
     private void copyHeaders(Request smartyRequest, HttpRequest httpRequest) {
         HttpHeaders httpHeaders = httpRequest.getHeaders();
 
-        Map<String, String> headers = smartyRequest.getHeaders();
+        Map<String, Object> headers = smartyRequest.getHeaders();
         for (String headerName : headers.keySet())
             httpHeaders.set(headerName, headers.get(headerName));
 
diff --git a/src/main/java/com/smartystreets/api/Request.java b/src/main/java/com/smartystreets/api/Request.java
index f84b446..42ebab0 100644
--- a/src/main/java/com/smartystreets/api/Request.java
+++ b/src/main/java/com/smartystreets/api/Request.java
@@ -7,7 +7,7 @@
 
 public class Request {
     private static final String CHARSET = "UTF-8";
-    private final Map<String, String> headers;
+    private final Map<String, Object> headers;
     private final Map<String, String> parameters;
     private String urlPrefix;
     private String method;
@@ -22,7 +22,7 @@ public Request() {
         this.contentType = "application/json";
     }
 
-    void putHeader(String name, String value) {
+    void putHeader(String name, Object value) {
         this.headers.put(name, value);
     }
 
@@ -65,7 +65,7 @@ public String getMethod() {
         return method;
     }
 
-    public Map<String, String> getHeaders() {
+    public Map<String, Object> getHeaders() {
         return this.headers;
     }
 
diff --git a/src/test/java/com/smartystreets/api/CustomHeaderSenderTest.java b/src/test/java/com/smartystreets/api/CustomHeaderSenderTest.java
index 39e9117..5350dd6 100644
--- a/src/test/java/com/smartystreets/api/CustomHeaderSenderTest.java
+++ b/src/test/java/com/smartystreets/api/CustomHeaderSenderTest.java
@@ -14,7 +14,7 @@ public class CustomHeaderSenderTest {
 
     @Test
     public void testAllCustomHeadersAreAddedToTheRequest() throws IOException, SmartyException {
-        HashMap<String, String> headers = new HashMap<>();
+        HashMap<String, Object> headers = new HashMap<>();
         headers.put("A", "1");
         headers.put("B", "2");
         RequestCapturingSender inner = new RequestCapturingSender();
@@ -23,7 +23,7 @@ public void testAllCustomHeadersAreAddedToTheRequest() throws IOException, Smart
 
         sender.send(request);
 
-        Map<String, String> requestHeaders = inner.getRequest().getHeaders();
+        Map<String, Object> requestHeaders = inner.getRequest().getHeaders();
         assertNotNull("There should be headers here.", requestHeaders);
         assertEquals(headers.get("A"), inner.getRequest().getHeaders().get("A"));
 
diff --git a/src/test/java/com/smartystreets/api/GoogleSenderTest.java b/src/test/java/com/smartystreets/api/GoogleSenderTest.java
index 1a1c489..e696ae4 100644
--- a/src/test/java/com/smartystreets/api/GoogleSenderTest.java
+++ b/src/test/java/com/smartystreets/api/GoogleSenderTest.java
@@ -29,7 +29,7 @@ public void testHttpRequestContainsCorrectHeaders() throws Exception {
 
         sender.send(request);
 
-        Map<String, String> headers = request.getHeaders();
+        Map<String, Object> headers = request.getHeaders();
         assertEquals("value1", headers.get("X-name1"));
         assertEquals("value2", headers.get("X-name2"));
     }