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 ee5c2956..7a53c6c8 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
@@ -190,6 +190,7 @@ public class DefaultConnection implements Connection {
 
             jws.setAlgorithmHeaderValue(keyAlgorithm(jwk));
             jws.setKey(keypair.getPrivate());
+            jws.sign();
 
             if (LOG.isDebugEnabled()) {
                 LOG.debug("POST {}", url);
@@ -197,7 +198,11 @@ public class DefaultConnection implements Connection {
                 LOG.debug("  JWS Header: {}", jws.getHeaders().getFullHeaderAsJsonString());
             }
 
-            byte[] outputData = jws.getCompactSerialization().getBytes(DEFAULT_CHARSET);
+            JSONBuilder jb = new JSONBuilder();
+            jb.put("protected", jws.getHeaders().getEncodedHeader());
+            jb.put("payload", jws.getEncodedPayload());
+            jb.put("signature", jws.getEncodedSignature());
+            byte[] outputData = jb.toString().getBytes(DEFAULT_CHARSET);
 
             conn.setFixedLengthStreamingMode(outputData.length);
             conn.connect();
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 0957f11c..f434393f 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
@@ -689,11 +689,10 @@ public class DefaultConnectionTest {
         verify(mockUrlConnection, atLeast(0)).getHeaderFields();
         verifyNoMoreInteractions(mockUrlConnection);
 
-        String serialized = new String(outputStream.toByteArray(), "utf-8");
-        String[] written = CompactSerializer.deserialize(serialized);
-        String header = Base64Url.decodeToUtf8String(written[0]);
-        String claims = Base64Url.decodeToUtf8String(written[1]);
-        String signature = written[2];
+        JSON data = JSON.parse(new String(outputStream.toByteArray(), "utf-8"));
+        String encodedHeader = data.get("protected").asString();
+        String encodedSignature = data.get("signature").asString();
+        String encodedPayload = data.get("payload").asString();
 
         StringBuilder expectedHeader = new StringBuilder();
         expectedHeader.append('{');
@@ -703,12 +702,12 @@ public class DefaultConnectionTest {
         expectedHeader.append("\"kid\":\"").append(keyIdentifier).append('"');
         expectedHeader.append('}');
 
-        assertThat(header, sameJSONAs(expectedHeader.toString()));
-        assertThat(claims, sameJSONAs("{\"foo\":123,\"bar\":\"a-string\"}"));
-        assertThat(signature, not(isEmptyOrNullString()));
+        assertThat(Base64Url.decodeToUtf8String(encodedHeader), sameJSONAs(expectedHeader.toString()));
+        assertThat(Base64Url.decodeToUtf8String(encodedPayload), sameJSONAs("{\"foo\":123,\"bar\":\"a-string\"}"));
+        assertThat(encodedSignature, not(isEmptyOrNullString()));
 
         JsonWebSignature jws = new JsonWebSignature();
-        jws.setCompactSerialization(serialized);
+        jws.setCompactSerialization(CompactSerializer.serialize(encodedHeader, encodedPayload, encodedSignature));
         jws.setKey(session.getKeyPair().getPublic());
         assertThat(jws.verifySignature(), is(true));
     }
@@ -762,11 +761,10 @@ public class DefaultConnectionTest {
         verify(mockUrlConnection, atLeast(0)).getHeaderFields();
         verifyNoMoreInteractions(mockUrlConnection);
 
-        String serialized = new String(outputStream.toByteArray(), "utf-8");
-        String[] written = CompactSerializer.deserialize(serialized);
-        String header = Base64Url.decodeToUtf8String(written[0]);
-        String claims = Base64Url.decodeToUtf8String(written[1]);
-        String signature = written[2];
+        JSON data = JSON.parse(new String(outputStream.toByteArray(), "utf-8"));
+        String encodedHeader = data.get("protected").asString();
+        String encodedSignature = data.get("signature").asString();
+        String encodedPayload = data.get("payload").asString();
 
         StringBuilder expectedHeader = new StringBuilder();
         expectedHeader.append('{');
@@ -779,12 +777,12 @@ public class DefaultConnectionTest {
         expectedHeader.append("\"n\":\"").append(TestUtils.N).append("\"");
         expectedHeader.append("}}");
 
-        assertThat(header, sameJSONAs(expectedHeader.toString()));
-        assertThat(claims, sameJSONAs("{\"foo\":123,\"bar\":\"a-string\"}"));
-        assertThat(signature, not(isEmptyOrNullString()));
+        assertThat(Base64Url.decodeToUtf8String(encodedHeader), sameJSONAs(expectedHeader.toString()));
+        assertThat(Base64Url.decodeToUtf8String(encodedPayload), sameJSONAs("{\"foo\":123,\"bar\":\"a-string\"}"));
+        assertThat(encodedSignature, not(isEmptyOrNullString()));
 
         JsonWebSignature jws = new JsonWebSignature();
-        jws.setCompactSerialization(serialized);
+        jws.setCompactSerialization(CompactSerializer.serialize(encodedHeader, encodedPayload, encodedSignature));
         jws.setKey(session.getKeyPair().getPublic());
         assertThat(jws.verifySignature(), is(true));
     }