diff --git a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/ParameterParser.java b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/ParameterParser.java
index 1be1c03f19..7c41638474 100644
--- a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/ParameterParser.java
+++ b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/ParameterParser.java
@@ -14,8 +14,8 @@
 
 package com.google.gerrit.httpd.restapi;
 
+import static com.google.gerrit.httpd.restapi.RestApiServlet.replyBinaryResult;
 import static com.google.gerrit.httpd.restapi.RestApiServlet.replyError;
-import static com.google.gerrit.httpd.restapi.RestApiServlet.replyText;
 import static javax.servlet.http.HttpServletResponse.SC_BAD_REQUEST;
 
 import com.google.common.annotations.VisibleForTesting;
@@ -26,6 +26,7 @@ import com.google.common.collect.Iterables;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Sets;
 import com.google.gerrit.extensions.restapi.BadRequestException;
+import com.google.gerrit.extensions.restapi.BinaryResult;
 import com.google.gerrit.server.util.Url;
 import com.google.gerrit.util.cli.CmdLineParser;
 import com.google.gson.JsonArray;
@@ -78,7 +79,8 @@ class ParameterParser {
       msg.write('\n');
       clp.printUsage(msg, null);
       msg.write('\n');
-      replyText(req, res, msg.toString());
+      replyBinaryResult(req, res,
+          BinaryResult.create(msg.toString()).setContentType("text/plain"));
       return false;
     }
 
diff --git a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/RestApiServlet.java b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
index 8057346443..715300ac3b 100644
--- a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
+++ b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/RestApiServlet.java
@@ -494,7 +494,7 @@ public class RestApiServlet extends HttpServlet {
     }
   }
 
-  private static void replyBinaryResult(
+  static void replyBinaryResult(
       @Nullable HttpServletRequest req,
       HttpServletResponse res,
       BinaryResult bin) throws IOException {