--- a/mobile/android/base/java/org/mozilla/gecko/util/FileUtils.java
+++ b/mobile/android/base/java/org/mozilla/gecko/util/FileUtils.java
@@ -10,16 +10,17 @@ import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.FilenameFilter;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
 import java.nio.charset.Charset;
 import java.util.Scanner;
 
+import org.json.JSONObject;
 import org.mozilla.gecko.annotation.RobocopTarget;
 
 public class FileUtils {
     private static final String LOGTAG = "GeckoFileUtils";
     /*
     * A basic Filter for checking a filename and age.
     **/
     static public class NameAndAgeFilter implements FilenameFilter {
@@ -96,16 +97,24 @@ public class FileUtils {
         } finally {
             if (scanner != null) {
                 scanner.close();
             }
         }
     }
 
     /**
+     * A generic solution to write a JSONObject to a file.
+     * See {@link #writeStringToFile(File, String)} for more details.
+     */
+    public static void writeJSONObjectToFile(final File file, final JSONObject obj) throws IOException {
+        writeStringToFile(file, obj.toString());
+    }
+
+    /**
      * A generic solution to write to a File - the given file will be overwritten.
      * See {@link #writeStringToOutputStreamAndCloseStream(OutputStream, String)} for more details.
      */
     public static void writeStringToFile(final File file, final String str) throws IOException {
         writeStringToOutputStreamAndCloseStream(new FileOutputStream(file, false), str);
     }
 
     /**
@@ -120,10 +129,9 @@ public class FileUtils {
             throws IOException {
         final OutputStreamWriter writer = new OutputStreamWriter(outputStream, Charset.forName("UTF-8"));
         try {
             writer.write(str);
         } finally {
             writer.close();
         }
     }
-
 }

--- a/mobile/android/tests/background/junit4/src/org/mozilla/gecko/TestGeckoProfile.java
+++ b/mobile/android/tests/background/junit4/src/org/mozilla/gecko/TestGeckoProfile.java
@@ -123,17 +123,17 @@ public class TestGeckoProfile {
     }
 
     @Test
     public void testGetClientIdMissingClientIdJSONAttr() throws Exception {
         final String validClientId = "905de1c0-0ea6-4a43-95f9-6170035f5a82";
         final JSONObject objMissingClientId = new JSONObject();
         objMissingClientId.put("irrelevantKey", validClientId);
         assertTrue("Created the parent dirs of the client ID file", clientIdFile.getParentFile().mkdirs());
-        FileUtil.writeJSONObjectToFile(clientIdFile, objMissingClientId);
+        FileUtils.writeJSONObjectToFile(clientIdFile, objMissingClientId);
 
         final String clientIdForMissingAttr = profile.getClientId();
         assertValidClientId(clientIdForMissingAttr);
         assertNotEquals("Did not use other attr when JSON attr was missing", validClientId, clientIdForMissingAttr);
     }
 
     @Test
     public void testGetClientIdInvalidIdFileFormat() throws Exception {
@@ -205,17 +205,17 @@ public class TestGeckoProfile {
         }
     }
 
     @Test
     public void testGetProfileCreationDateFromTimesFile() throws Exception {
         final long expectedDate = System.currentTimeMillis();
         final JSONObject expectedObj = new JSONObject();
         expectedObj.put(PROFILE_CREATION_DATE_JSON_ATTR, expectedDate);
-        FileUtil.writeJSONObjectToFile(timesFile, expectedObj);
+        FileUtils.writeJSONObjectToFile(timesFile, expectedObj);
 
         final Context context = RuntimeEnvironment.application;
         final long actualDate = profile.getAndPersistProfileCreationDate(context);
         assertEquals("Date from disk equals date inserted to disk", expectedDate, actualDate);
 
         final long actualDateFromDisk = readProfileCreationDateFromFile(timesFile);
         assertEquals("Date in times.json has not changed after accessing profile creation date",
                 expectedDate, actualDateFromDisk);
@@ -245,11 +245,11 @@ public class TestGeckoProfile {
     private String readClientIdFromFile(final File file) throws Exception {
         final JSONObject obj = FileUtil.readJSONObjectFromFile(file);
         return obj.getString(CLIENT_ID_JSON_ATTR);
     }
 
     private void writeClientIdToFile(final File file, final String clientId) throws Exception {
         final JSONObject obj = new JSONObject();
         obj.put(CLIENT_ID_JSON_ATTR, clientId);
-        FileUtil.writeJSONObjectToFile(file, obj);
+        FileUtils.writeJSONObjectToFile(file, obj);
     }
 }

--- a/mobile/android/tests/background/junit4/src/org/mozilla/gecko/helpers/FileUtil.java
+++ b/mobile/android/tests/background/junit4/src/org/mozilla/gecko/helpers/FileUtil.java
@@ -22,14 +22,9 @@ public class FileUtil {
             while (scanner.hasNext()) {
                 builder.append(scanner.next());
             }
         } finally {
             scanner.close();
         }
         return new JSONObject(builder.toString());
     }
-
-    public static void writeJSONObjectToFile(final File file, final JSONObject obj) throws Exception {
-        FileUtils.writeStringToFile(file, obj.toString());
-    }
-
 }

--- a/mobile/android/tests/background/junit4/src/org/mozilla/gecko/util/TestFileUtils.java
+++ b/mobile/android/tests/background/junit4/src/org/mozilla/gecko/util/TestFileUtils.java
@@ -1,16 +1,17 @@
 /*
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, you can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
 package org.mozilla.gecko.util;
 
+import org.json.JSONObject;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
 import org.junit.runner.RunWith;
 import org.mozilla.gecko.background.testhelpers.TestRunner;
 
 import java.io.File;
@@ -64,16 +65,37 @@ public class TestFileUtils {
     public void testWriteStringToFile() throws Exception {
         final String expected = "String to write contains hard characters: !\n \\s..\"'\u00f1";
         FileUtils.writeStringToFile(testFile, expected);
 
         assertTrue("Written file exists", testFile.exists());
         assertEquals("Read data equals written data", expected, readStringFromFile(testFile, expected.length()));
     }
 
+    @Test
+    public void testWriteJSONObjectToFile() throws Exception {
+        final JSONObject expected = new JSONObject()
+                .put("int", 1)
+                .put("str", "1")
+                .put("bool", true)
+                .put("null", JSONObject.NULL)
+                .put("raw null", null);
+        FileUtils.writeJSONObjectToFile(testFile, expected);
+
+        assertTrue("Written file exists", testFile.exists());
+
+        // JSONObject.equals compares references so we have to assert each key individually. >:(
+        final JSONObject actual = new JSONObject(readStringFromFile(testFile, (int) testFile.length()));
+        assertEquals(1, actual.getInt("int"));
+        assertEquals("1", actual.getString("str"));
+        assertEquals(true, actual.getBoolean("bool"));
+        assertEquals(JSONObject.NULL, actual.get("null"));
+        assertFalse(actual.has("raw null"));
+    }
+
     // Since the read methods may not be tested yet.
     private static String readStringFromFile(final File file, final int bufferLen) throws IOException {
         final char[] buffer = new char[bufferLen];
         try (InputStreamReader reader = new InputStreamReader(new FileInputStream(file), Charset.forName("UTF-8"))) {
             reader.read(buffer, 0, buffer.length);
         }
         return new String(buffer);
     }