diff --git a/websocket-resources/src/main/java/org/whispersystems/websocket/WebSocketResourceProvider.java b/websocket-resources/src/main/java/org/whispersystems/websocket/WebSocketResourceProvider.java
index e75708d79..6cabf7b15 100644
--- a/websocket-resources/src/main/java/org/whispersystems/websocket/WebSocketResourceProvider.java
+++ b/websocket-resources/src/main/java/org/whispersystems/websocket/WebSocketResourceProvider.java
@@ -36,6 +36,7 @@ import org.whispersystems.websocket.session.ContextPrincipal;
 import org.whispersystems.websocket.session.WebSocketSessionContext;
 import org.whispersystems.websocket.setup.WebSocketConnectListener;
 
+import javax.ws.rs.core.MultivaluedMap;
 import javax.ws.rs.core.Response;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
@@ -197,7 +198,7 @@ public class WebSocketResourceProvider<T extends Principal> implements WebSocket
       byte[] responseBytes = messageFactory.createResponse(requestMessage.getRequestId(),
                                                            response.getStatus(),
                                                            response.getStatusInfo().getReasonPhrase(),
-                                                           new LinkedList<>(),
+                                                           getHeaderList(response.getStringHeaders()),
                                                            Optional.ofNullable(body))
                                            .toByteArray();
 
@@ -207,16 +208,10 @@ public class WebSocketResourceProvider<T extends Principal> implements WebSocket
 
   private void sendErrorResponse(WebSocketRequestMessage requestMessage, Response error) {
     if (requestMessage.hasRequestId()) {
-      List<String> headers = new LinkedList<>();
-
-      for (String key : error.getStringHeaders().keySet()) {
-        headers.add(key + ":" + error.getStringHeaders().getFirst(key));
-      }
-
       WebSocketMessage response = messageFactory.createResponse(requestMessage.getRequestId(),
                                                                 error.getStatus(),
                                                                 "Error response",
-                                                                headers,
+                                                                getHeaderList(error.getStringHeaders()),
                                                                 Optional.empty());
 
       remoteEndpoint.sendBytesByFuture(ByteBuffer.wrap(response.toByteArray()));
@@ -229,4 +224,16 @@ public class WebSocketResourceProvider<T extends Principal> implements WebSocket
     return context;
   }
 
+  @VisibleForTesting
+  static List<String> getHeaderList(final MultivaluedMap<String, String> headerMap) {
+    final List<String> headers = new LinkedList<>();
+
+    if (headerMap != null) {
+      for (String key : headerMap.keySet()) {
+        headers.add(key + ":" + headerMap.getFirst(key));
+      }
+    }
+
+    return headers;
+  }
 }
diff --git a/websocket-resources/src/test/java/org/whispersystems/websocket/WebSocketResourceProviderTest.java b/websocket-resources/src/test/java/org/whispersystems/websocket/WebSocketResourceProviderTest.java
index a5d874733..803fecc1b 100644
--- a/websocket-resources/src/test/java/org/whispersystems/websocket/WebSocketResourceProviderTest.java
+++ b/websocket-resources/src/test/java/org/whispersystems/websocket/WebSocketResourceProviderTest.java
@@ -36,19 +36,21 @@ import javax.ws.rs.Path;
 import javax.ws.rs.PathParam;
 import javax.ws.rs.Produces;
 import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.MultivaluedHashMap;
+import javax.ws.rs.core.MultivaluedMap;
 import javax.ws.rs.core.Response;
 import javax.ws.rs.ext.ExceptionMapper;
 import javax.ws.rs.ext.Provider;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
 import java.security.Principal;
+import java.util.Arrays;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 
 import io.dropwizard.auth.Auth;
-import io.dropwizard.auth.AuthValueFactoryProvider;
 import io.dropwizard.jersey.DropwizardResourceConfig;
 import io.dropwizard.jersey.jackson.JacksonMessageBodyProvider;
 import static org.assertj.core.api.Assertions.assertThat;
@@ -585,6 +587,21 @@ public class WebSocketResourceProviderTest {
     assertThat(response.getBody().toStringUtf8()).isEqualTo("my response");
   }
 
+  @Test
+  public void testGetHeaderList() {
+    assertThat(WebSocketResourceProvider.getHeaderList(new MultivaluedHashMap<>())).isEmpty();
+
+    {
+      final MultivaluedMap<String, String> headers = new MultivaluedHashMap<>();
+      headers.put("test", Arrays.asList("a", "b", "c"));
+
+      final List<String> headerStrings = WebSocketResourceProvider.getHeaderList(headers);
+
+      assertThat(headerStrings).hasSize(1);
+      assertThat(headerStrings).contains("test:a");
+    }
+  }
+
   private SubProtocol.WebSocketResponseMessage getResponse(ArgumentCaptor<ByteBuffer> responseCaptor) throws InvalidProtocolBufferException {
     return SubProtocol.WebSocketMessage.parseFrom(responseCaptor.getValue().array()).getResponse();
   }