diff --git a/MyTracks/src/com/google/android/apps/mytracks/io/backup/ExternalFileBackup.java b/MyTracks/src/com/google/android/apps/mytracks/io/backup/ExternalFileBackup.java
index a5e33ff1f..e572a4bf2 100644
--- a/MyTracks/src/com/google/android/apps/mytracks/io/backup/ExternalFileBackup.java
+++ b/MyTracks/src/com/google/android/apps/mytracks/io/backup/ExternalFileBackup.java
@@ -40,6 +40,7 @@ import java.text.SimpleDateFormat;
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
 import java.util.TimeZone;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
@@ -52,8 +53,8 @@ import java.util.zip.ZipOutputStream;
  */
 class ExternalFileBackup {
   // Filename format - in UTC
-  private static final SimpleDateFormat BACKUP_FILENAME_FORMAT =
-      new SimpleDateFormat("'backup-'yyyy-MM-dd_HH-mm-ss'.zip'");
+  private static final SimpleDateFormat BACKUP_FILENAME_FORMAT = new SimpleDateFormat(
+      "'backup-'yyyy-MM-dd_HH-mm-ss'.zip'", Locale.US);
   static {
     BACKUP_FILENAME_FORMAT.setTimeZone(TimeZone.getTimeZone("UTC"));
   }
diff --git a/MyTracksTest/src/com/google/android/apps/mytracks/util/TrackNameUtilsTest.java b/MyTracksTest/src/com/google/android/apps/mytracks/util/TrackNameUtilsTest.java
index 1502ded75..202ec0922 100644
--- a/MyTracksTest/src/com/google/android/apps/mytracks/util/TrackNameUtilsTest.java
+++ b/MyTracksTest/src/com/google/android/apps/mytracks/util/TrackNameUtilsTest.java
@@ -22,6 +22,7 @@ import android.test.AndroidTestCase;
 
 import java.text.SimpleDateFormat;
 import java.util.Date;
+import java.util.Locale;
 
 /**
  * Tests {@link TrackNameUtils}.
@@ -51,7 +52,8 @@ public class TrackNameUtilsTest extends AndroidTestCase {
   public void testTrackName_date_iso_8601() {
     PreferencesUtils.setString(getContext(), R.string.track_name_key,
         getContext().getString(R.string.settings_recording_track_name_date_iso_8601_value));
-    SimpleDateFormat simpleDateFormat = new SimpleDateFormat(TrackNameUtils.ISO_8601_FORMAT);
+    SimpleDateFormat simpleDateFormat = new SimpleDateFormat(
+        TrackNameUtils.ISO_8601_FORMAT, Locale.US);
     assertEquals(simpleDateFormat.format(new Date(START_TIME)),
         TrackNameUtils.getTrackName(getContext(), TRACK_ID, START_TIME, null));
   }