diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/Certificate.java b/acme4j-client/src/main/java/org/shredzone/acme4j/Certificate.java
index 058715cf..d340dacb 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/Certificate.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/Certificate.java
@@ -71,7 +71,7 @@ public class Certificate extends AcmeResource {
         if (certChain == null) {
             LOG.debug("download");
             try (Connection conn = connect()) {
-                conn.sendRequest(getLocation(), getSession());
+                conn.sendCertificateRequest(getLocation(), getSession());
                 alternates = new ArrayList<>(conn.getLinks("alternate"));
                 certChain = new ArrayList<>(conn.readCertificates());
             }
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/Connection.java b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/Connection.java
index 2d53bb96..092e56d9 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/Connection.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/Connection.java
@@ -57,6 +57,19 @@ public interface Connection extends AutoCloseable {
      */
     void sendRequest(URL url, Session session) throws AcmeException;
 
+    /**
+     * Sends a request for a certificate resource.
+     * <p>
+     * If the response code was not {@link HttpURLConnection#HTTP_OK}, an
+     * {@link AcmeException} matching the error is raised.
+     *
+     * @param url
+     *            {@link URL} to send the request to.
+     * @param session
+     *            {@link Session} instance to be used for tracking
+     */
+    void sendCertificateRequest(URL url, Session session) throws AcmeException;
+
     /**
      * Sends a signed POST request. Requires a {@link Login} for the session and
      * {@link KeyPair}. The {@link Login} account location is sent in a "kid" protected
diff --git a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java
index fce470ef..ee5900dd 100644
--- a/acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java
+++ b/acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java
@@ -78,6 +78,9 @@ public class DefaultConnection implements Connection {
     private static final String REPLAY_NONCE_HEADER = "Replay-Nonce";
     private static final String RETRY_AFTER_HEADER = "Retry-After";
     private static final String DEFAULT_CHARSET = "utf-8";
+    private static final String MIME_JSON = "application/json";
+    private static final String MIME_JSON_PROBLEM = "application/problem+json";
+    private static final String MIME_CERTIFICATE_CHAIN = "application/pem-certificate-chain";
 
     private static final Pattern BASE64URL_PATTERN = Pattern.compile("[0-9A-Za-z_-]+");
 
@@ -134,6 +137,15 @@ public class DefaultConnection implements Connection {
 
     @Override
     public void sendRequest(URL url, Session session) throws AcmeException {
+        sendRequest(url, session, MIME_JSON);
+    }
+
+    @Override
+    public void sendCertificateRequest(URL url, Session session) throws AcmeException {
+        sendRequest(url, session, MIME_CERTIFICATE_CHAIN);
+    }
+
+    private void sendRequest(URL url, Session session, String accept) throws AcmeException {
         Objects.requireNonNull(url, "url");
         Objects.requireNonNull(session, "session");
         assertConnectionIsClosed();
@@ -143,6 +155,7 @@ public class DefaultConnection implements Connection {
         try {
             conn = httpConnector.openConnection(url, session.getProxy());
             conn.setRequestMethod("GET");
+            conn.setRequestProperty(ACCEPT_HEADER, accept);
             conn.setRequestProperty(ACCEPT_CHARSET_HEADER, DEFAULT_CHARSET);
             conn.setRequestProperty(ACCEPT_LANGUAGE_HEADER, session.getLocale().toLanguageTag());
             conn.setDoOutput(false);
@@ -207,8 +220,7 @@ public class DefaultConnection implements Connection {
         }
 
         String contentType = AcmeUtils.getContentType(conn.getHeaderField(CONTENT_TYPE_HEADER));
-        if (!("application/json".equals(contentType)
-                    || "application/problem+json".equals(contentType))) {
+        if (!(MIME_JSON.equals(contentType) || MIME_JSON_PROBLEM.equals(contentType))) {
             throw new AcmeProtocolException("Unexpected content type: " + contentType);
         }
 
@@ -233,7 +245,7 @@ public class DefaultConnection implements Connection {
         assertConnectionIsOpen();
 
         String contentType = AcmeUtils.getContentType(conn.getHeaderField(CONTENT_TYPE_HEADER));
-        if (!("application/pem-certificate-chain".equals(contentType))) {
+        if (!(MIME_CERTIFICATE_CHAIN.equals(contentType))) {
             throw new AcmeProtocolException("Unexpected content type: " + contentType);
         }
 
@@ -330,7 +342,7 @@ public class DefaultConnection implements Connection {
 
             conn = httpConnector.openConnection(url, session.getProxy());
             conn.setRequestMethod("POST");
-            conn.setRequestProperty(ACCEPT_HEADER, "application/json");
+            conn.setRequestProperty(ACCEPT_HEADER, MIME_JSON);
             conn.setRequestProperty(ACCEPT_CHARSET_HEADER, DEFAULT_CHARSET);
             conn.setRequestProperty(ACCEPT_LANGUAGE_HEADER, session.getLocale().toLanguageTag());
             conn.setRequestProperty(CONTENT_TYPE_HEADER, "application/jose+json");
diff --git a/acme4j-client/src/test/java/org/shredzone/acme4j/CertificateTest.java b/acme4j-client/src/test/java/org/shredzone/acme4j/CertificateTest.java
index eb2c0144..44221e8b 100644
--- a/acme4j-client/src/test/java/org/shredzone/acme4j/CertificateTest.java
+++ b/acme4j-client/src/test/java/org/shredzone/acme4j/CertificateTest.java
@@ -55,7 +55,7 @@ public class CertificateTest {
 
         TestableConnectionProvider provider = new TestableConnectionProvider() {
             @Override
-            public void sendRequest(URL url, Session session) {
+            public void sendCertificateRequest(URL url, Session session) {
                 assertThat(url, is(locationUrl));
                 assertThat(session, is(notNullValue()));
             }
@@ -124,7 +124,7 @@ public class CertificateTest {
             private boolean certRequested = false;
 
             @Override
-            public void sendRequest(URL url, Session session) {
+            public void sendCertificateRequest(URL url, Session session) {
                 assertThat(url, is(locationUrl));
                 assertThat(session, is(notNullValue()));
                 certRequested = true;
@@ -171,7 +171,7 @@ public class CertificateTest {
             private boolean certRequested = false;
 
             @Override
-            public void sendRequest(URL url, Session session) {
+            public void sendCertificateRequest(URL url, Session session) {
                 assertThat(url, is(locationUrl));
                 assertThat(session, is(notNullValue()));
                 certRequested = true;
diff --git a/acme4j-client/src/test/java/org/shredzone/acme4j/connector/DefaultConnectionTest.java b/acme4j-client/src/test/java/org/shredzone/acme4j/connector/DefaultConnectionTest.java
index 5ae7595a..55dea37b 100644
--- a/acme4j-client/src/test/java/org/shredzone/acme4j/connector/DefaultConnectionTest.java
+++ b/acme4j-client/src/test/java/org/shredzone/acme4j/connector/DefaultConnectionTest.java
@@ -653,6 +653,29 @@ public class DefaultConnectionTest {
         }
 
         verify(mockUrlConnection).setRequestMethod("GET");
+        verify(mockUrlConnection).setRequestProperty("Accept", "application/json");
+        verify(mockUrlConnection).setRequestProperty("Accept-Charset", "utf-8");
+        verify(mockUrlConnection).setRequestProperty("Accept-Language", "ja-JP");
+        verify(mockUrlConnection).setDoOutput(false);
+        verify(mockUrlConnection).connect();
+        verify(mockUrlConnection).getResponseCode();
+        verify(mockUrlConnection, atLeast(0)).getHeaderFields();
+        verifyNoMoreInteractions(mockUrlConnection);
+    }
+
+    /**
+     * Test certificate GET requests.
+     */
+    @Test
+    public void testSendCertificateRequest() throws Exception {
+        when(mockUrlConnection.getResponseCode()).thenReturn(HttpURLConnection.HTTP_OK);
+
+        try (DefaultConnection conn = new DefaultConnection(mockHttpConnection)) {
+            conn.sendCertificateRequest(requestUrl, session);
+        }
+
+        verify(mockUrlConnection).setRequestMethod("GET");
+        verify(mockUrlConnection).setRequestProperty("Accept", "application/pem-certificate-chain");
         verify(mockUrlConnection).setRequestProperty("Accept-Charset", "utf-8");
         verify(mockUrlConnection).setRequestProperty("Accept-Language", "ja-JP");
         verify(mockUrlConnection).setDoOutput(false);
diff --git a/acme4j-client/src/test/java/org/shredzone/acme4j/connector/DummyConnection.java b/acme4j-client/src/test/java/org/shredzone/acme4j/connector/DummyConnection.java
index 2bfe67ee..f3821134 100644
--- a/acme4j-client/src/test/java/org/shredzone/acme4j/connector/DummyConnection.java
+++ b/acme4j-client/src/test/java/org/shredzone/acme4j/connector/DummyConnection.java
@@ -41,6 +41,11 @@ public class DummyConnection implements Connection {
         throw new UnsupportedOperationException();
     }
 
+    @Override
+    public void sendCertificateRequest(URL url, Session session) throws AcmeException {
+        throw new UnsupportedOperationException();
+    }
+
     @Override
     public int sendSignedRequest(URL url, JSONBuilder claims, Login login)
                 throws AcmeException {