diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
index 1084291..28aa06f 100644
--- a/PREUPLOAD.cfg
+++ b/PREUPLOAD.cfg
@@ -7,5 +7,4 @@
 
 [Hook Scripts]
 checkstyle_hook = ${REPO_ROOT}/prebuilts/checkstyle/checkstyle.py --sha ${PREUPLOAD_COMMIT}
-                  -fw updater_sample/
-
+                  --file_whitelist tools/ updater_sample/
diff --git a/tools/image_generator/ImageGenerator.java b/tools/image_generator/ImageGenerator.java
index 8ed696a..8cdd494 100644
--- a/tools/image_generator/ImageGenerator.java
+++ b/tools/image_generator/ImageGenerator.java
@@ -16,6 +16,16 @@
 
 package com.android.recovery.tools;
 
+import org.apache.commons.cli.CommandLine;
+import org.apache.commons.cli.GnuParser;
+import org.apache.commons.cli.HelpFormatter;
+import org.apache.commons.cli.OptionBuilder;
+import org.apache.commons.cli.Options;
+import org.apache.commons.cli.ParseException;
+import org.w3c.dom.Document;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
 import java.awt.Color;
 import java.awt.Font;
 import java.awt.FontFormatException;
@@ -32,25 +42,14 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
-import java.util.TreeMap;
 import java.util.StringTokenizer;
+import java.util.TreeMap;
 
 import javax.imageio.ImageIO;
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;
 
-import org.apache.commons.cli.CommandLine;
-import org.apache.commons.cli.GnuParser;
-import org.apache.commons.cli.HelpFormatter;
-import org.apache.commons.cli.OptionBuilder;
-import org.apache.commons.cli.Options;
-import org.apache.commons.cli.ParseException;
-
-import org.w3c.dom.Document;
-import org.w3c.dom.Node;
-import org.w3c.dom.NodeList;
-
 /**
  * Command line tool to generate the localized image for recovery mode.
  */
@@ -552,4 +551,3 @@
     imageGenerator.generateImage(localizedStringMap, cmd.getOptionValue("output_file"));
   }
 }
-