diff --git a/http-requests-core/src/main/java/com/budjb/httprequests/HttpRequest.java b/http-requests-core/src/main/java/com/budjb/httprequests/HttpRequest.java
index 16f61c6..6444b96 100644
--- a/http-requests-core/src/main/java/com/budjb/httprequests/HttpRequest.java
+++ b/http-requests-core/src/main/java/com/budjb/httprequests/HttpRequest.java
@@ -86,7 +86,7 @@ public HttpRequest() {
      *
      * @param uri URI of the request.
      */
-    public HttpRequest(URI uri) {
+    public HttpRequest(URI uri) throws URISyntaxException {
         parseUri(uri);
     }
 
@@ -131,7 +131,7 @@ public HttpRequest setUri(String uri) throws URISyntaxException {
      * @param uri URI of the request.
      * @return The instance of this class the method was called with.
      */
-    public HttpRequest setUri(URI uri) {
+    public HttpRequest setUri(URI uri) throws URISyntaxException {
         parseUri(uri);
         return this;
     }
@@ -416,17 +416,25 @@ private void parseUri(String uri) throws URISyntaxException {
      *
      * @param uri URI object to parse.
      */
-    private void parseUri(URI uri) {
+    private void parseUri(URI uri) throws URISyntaxException {
         String scheme = uri.getScheme();
         String host = uri.getHost();
         int port = uri.getPort();
         String path = uri.getRawPath();
         String query = uri.getQuery();
 
+        if (uri.getScheme() == null) {
+            throw new URISyntaxException(uri.toString(), "URI must contain a scheme");
+        }
+
+        if (uri.getHost() == null) {
+            throw new URISyntaxException(uri.toString(), "URI must contain a host");
+        }
+
         StringBuilder builder = new StringBuilder(scheme).append("://").append(host);
 
         if (port != -1 && !(scheme.equalsIgnoreCase("https") && port == 443) && !(scheme.equalsIgnoreCase("http") && port == 80)) {
-            builder = builder.append(':').append(port);
+            builder.append(':').append(port);
         }
 
         builder.append(path);
diff --git a/http-requests-core/src/main/java/com/budjb/httprequests/converter/EntityConverterManager.java b/http-requests-core/src/main/java/com/budjb/httprequests/converter/EntityConverterManager.java
index d34d7d5..3d08bb3 100644
--- a/http-requests-core/src/main/java/com/budjb/httprequests/converter/EntityConverterManager.java
+++ b/http-requests-core/src/main/java/com/budjb/httprequests/converter/EntityConverterManager.java
@@ -130,6 +130,10 @@ public HttpEntity write(ConvertingHttpEntity entity) throws UnsupportedConversio
      * @throws UnsupportedConversionException when there are no entity writers that support the object type.
      */
     public HttpEntity write(Object entity, String contentType, String characterSet) throws UnsupportedConversionException {
+        if (entity == null) {
+            return null;
+        }
+
         Class<?> type = entity.getClass();
 
         for (EntityWriter writer : getEntityWriters()) {
diff --git a/http-requests-documentation/src/docs/changelog.adoc b/http-requests-documentation/src/docs/changelog.adoc
index d7fcc53..5ffe114 100644
--- a/http-requests-documentation/src/docs/changelog.adoc
+++ b/http-requests-documentation/src/docs/changelog.adoc
@@ -9,6 +9,13 @@ The changelog will be updated with release notes for each release of the library
   precedence over a user-specified one.
 * Add http-requests-mock library to enable easier testing of code using
   the http-requests libraries.
+* Fix `NullPointerException` when sending a request with a null entity
+  (https://github.com/budjb/http-requests/issues/14[#14]).
+* Write a test to ensure that retrieving an entity when the response does not contain
+  an entity does not result in a `NullPointerException`
+  (https://github.com/budjb/http-requests/issues/13[#13]).
+* Throw a `URISyntaxException` instead of `NullPointerException` when a URI is not absolute
+  (https://github.com/budjb/http-requests/issues/12[#12]).
 
 2.0.6::
 
diff --git a/http-requests-functional-test/src/main/groovy/com/budjb/httprequests/HttpIntegrationTestSuiteSpec.groovy b/http-requests-functional-test/src/main/groovy/com/budjb/httprequests/HttpIntegrationTestSuiteSpec.groovy
index 5144696..c373539 100644
--- a/http-requests-functional-test/src/main/groovy/com/budjb/httprequests/HttpIntegrationTestSuiteSpec.groovy
+++ b/http-requests-functional-test/src/main/groovy/com/budjb/httprequests/HttpIntegrationTestSuiteSpec.groovy
@@ -222,7 +222,6 @@ abstract class HttpIntegrationTestSuiteSpec extends AbstractIntegrationSpec {
         formData.addField('foo', 'baz')
         formData.addField('key', 'value')
 
-
         when:
         def response = httpClientFactory.createHttpClient().post("${baseUrl}/testForm", formData)
 
@@ -617,6 +616,45 @@ abstract class HttpIntegrationTestSuiteSpec extends AbstractIntegrationSpec {
         response.getHeader('content-type') == 'foo/bar'
     }
 
+    def 'Sending a null request entity does not send any request entity'() {
+        setup:
+        HttpRequest request = new HttpRequest("${baseUrl}/testBasicPost")
+
+        when:
+        def response = httpClientFactory.createHttpClient().post(request, null)
+
+        then:
+        !response.hasEntity()
+    }
+
+    def 'Retrieving a response entity when the response does not contain and entity does not result in a NullPointerException'() {
+        setup:
+        HttpRequest request = new HttpRequest("${baseUrl}/testBasicPost")
+
+        when:
+        def response = httpClientFactory.createHttpClient().post(request, null)
+
+        then:
+        !response.hasEntity()
+        response.getEntity(String) == null
+    }
+
+    def 'Making a request with a URI that does not contain a scheme throws a URISyntaxException'() {
+        when:
+        httpClientFactory.createHttpClient().get('foobar')
+
+        then:
+        thrown URISyntaxException
+    }
+
+    def 'Making a request with a URI that does not contain a host throws a URISyntaxException'() {
+        when:
+        httpClientFactory.createHttpClient().get('https:///foo/bar')
+
+        then:
+        thrown URISyntaxException
+    }
+
     static class CloseableFilter implements HttpClientFilter, Closeable {
         boolean closed = false
 
diff --git a/http-requests-groovy/src/main/java/com/budjb/httprequests/groovy/HttpRequestDelegate.java b/http-requests-groovy/src/main/java/com/budjb/httprequests/groovy/HttpRequestDelegate.java
index 31e5eb2..0c540fe 100644
--- a/http-requests-groovy/src/main/java/com/budjb/httprequests/groovy/HttpRequestDelegate.java
+++ b/http-requests-groovy/src/main/java/com/budjb/httprequests/groovy/HttpRequestDelegate.java
@@ -58,7 +58,7 @@ public void uri(String uri) throws URISyntaxException {
      *
      * @param uri The URI of the request.
      */
-    public void uri(URI uri) {
+    public void uri(URI uri) throws URISyntaxException {
         httpRequest.setUri(uri);
     }