diff --git a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/RelativeDateFormatter.java b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/RelativeDateFormatter.java
index 7c62ed7..2f0df8c 100644
--- a/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/RelativeDateFormatter.java
+++ b/gerrit-gwtui-common/src/main/java/com/google/gerrit/client/RelativeDateFormatter.java
@@ -14,9 +14,6 @@
 
 package com.google.gerrit.client;
 
-import static com.google.gerrit.client.CommonConstants.C;
-import static com.google.gerrit.client.CommonMessages.M;
-
 import java.util.Date;
 
 /**
@@ -24,6 +21,9 @@
  * defined by {@code git log --relative-date}.
  */
 public class RelativeDateFormatter {
+  private static CommonConstants constants;
+  private static CommonMessages messages;
+
   static final long SECOND_IN_MILLIS = 1000;
   static final long MINUTE_IN_MILLIS = 60 * SECOND_IN_MILLIS;
   static final long HOUR_IN_MILLIS = 60 * MINUTE_IN_MILLIS;
@@ -32,6 +32,19 @@
   static final long MONTH_IN_MILLIS = 30 * DAY_IN_MILLIS;
   static final long YEAR_IN_MILLIS = 365 * DAY_IN_MILLIS;
 
+  static void setConstants(CommonConstants c, CommonMessages m) {
+    constants = c;
+    messages = m;
+  }
+
+  private static CommonConstants c() {
+    return constants != null ? constants : CommonConstants.C;
+  }
+
+  private static CommonMessages m() {
+    return messages != null ? messages : CommonMessages.M;
+  }
+
   /**
    * @param when {@link Date} to format
    * @return age of given {@link Date} compared to now formatted in the same relative format as
@@ -42,81 +55,81 @@
 
     // shouldn't happen in a perfect world
     if (ageMillis < 0) {
-      return C.inTheFuture();
+      return c().inTheFuture();
     }
 
     // seconds
     if (ageMillis < upperLimit(MINUTE_IN_MILLIS)) {
       long seconds = round(ageMillis, SECOND_IN_MILLIS);
       if (seconds == 1) {
-        return C.oneSecondAgo();
+        return c().oneSecondAgo();
       }
-      return M.secondsAgo(seconds);
+      return m().secondsAgo(seconds);
     }
 
     // minutes
     if (ageMillis < upperLimit(HOUR_IN_MILLIS)) {
       long minutes = round(ageMillis, MINUTE_IN_MILLIS);
       if (minutes == 1) {
-        return C.oneMinuteAgo();
+        return c().oneMinuteAgo();
       }
-      return M.minutesAgo(minutes);
+      return m().minutesAgo(minutes);
     }
 
     // hours
     if (ageMillis < upperLimit(DAY_IN_MILLIS)) {
       long hours = round(ageMillis, HOUR_IN_MILLIS);
       if (hours == 1) {
-        return C.oneHourAgo();
+        return c().oneHourAgo();
       }
-      return M.hoursAgo(hours);
+      return m().hoursAgo(hours);
     }
 
     // up to 14 days use days
     if (ageMillis < 14 * DAY_IN_MILLIS) {
       long days = round(ageMillis, DAY_IN_MILLIS);
       if (days == 1) {
-        return C.oneDayAgo();
+        return c().oneDayAgo();
       }
-      return M.daysAgo(days);
+      return m().daysAgo(days);
     }
 
     // up to 10 weeks use weeks
     if (ageMillis < 10 * WEEK_IN_MILLIS) {
       long weeks = round(ageMillis, WEEK_IN_MILLIS);
       if (weeks == 1) {
-        return C.oneWeekAgo();
+        return c().oneWeekAgo();
       }
-      return M.weeksAgo(weeks);
+      return m().weeksAgo(weeks);
     }
 
     // months
     if (ageMillis < YEAR_IN_MILLIS) {
       long months = round(ageMillis, MONTH_IN_MILLIS);
       if (months == 1) {
-        return C.oneMonthAgo();
+        return c().oneMonthAgo();
       }
-      return M.monthsAgo(months);
+      return m().monthsAgo(months);
     }
 
     // up to 5 years use "year, months" rounded to months
     if (ageMillis < 5 * YEAR_IN_MILLIS) {
       long years = ageMillis / YEAR_IN_MILLIS;
-      String yearLabel = (years > 1) ? C.years() : C.year();
+      String yearLabel = (years > 1) ? c().years() : c().year();
       long months = round(ageMillis % YEAR_IN_MILLIS, MONTH_IN_MILLIS);
-      String monthLabel = (months > 1) ? C.months() : (months == 1 ? C.month() : "");
+      String monthLabel = (months > 1) ? c().months() : (months == 1 ? c().month() : "");
       if (months == 0) {
-        return M.years0MonthsAgo(years, yearLabel);
+        return m().years0MonthsAgo(years, yearLabel);
       }
-      return M.yearsMonthsAgo(years, yearLabel, months, monthLabel);
+      return m().yearsMonthsAgo(years, yearLabel, months, monthLabel);
     }
 
     // years
     long years = round(ageMillis, YEAR_IN_MILLIS);
     if (years == 1) {
-      return C.oneYearAgo();
+      return c().oneYearAgo();
     }
-    return M.yearsAgo(years);
+    return m().yearsAgo(years);
   }
 
   private static long upperLimit(long unit) {
diff --git a/gerrit-gwtui-common/src/test/java/com/google/gerrit/client/RelativeDateFormatterTest.java b/gerrit-gwtui-common/src/test/java/com/google/gerrit/client/RelativeDateFormatterTest.java
index 937fc96..513d95a 100644
--- a/gerrit-gwtui-common/src/test/java/com/google/gerrit/client/RelativeDateFormatterTest.java
+++ b/gerrit-gwtui-common/src/test/java/com/google/gerrit/client/RelativeDateFormatterTest.java
@@ -22,11 +22,23 @@
 import static org.junit.Assert.assertEquals;
 
 import java.util.Date;
-import org.eclipse.jgit.util.RelativeDateFormatter;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
 import org.junit.Test;
 
 public class RelativeDateFormatterTest {
 
+  @BeforeClass
+  public static void setConstants() {
+    Constants c = new Constants();
+    RelativeDateFormatter.setConstants(c, c);
+  }
+
+  @AfterClass
+  public static void unsetConstants() {
+    RelativeDateFormatter.setConstants(null, null);
+  }
+
   private static void assertFormat(long ageFromNow, long timeUnit, String expectedFormat) {
     Date d = new Date(System.currentTimeMillis() - ageFromNow * timeUnit);
     String s = RelativeDateFormatter.format(d);
@@ -41,7 +53,7 @@
 
   @Test
   public void formatSeconds() {
-    assertFormat(1, SECOND_IN_MILLIS, "1 seconds ago");
+    assertFormat(1, SECOND_IN_MILLIS, "1 second ago");
     assertFormat(89, SECOND_IN_MILLIS, "89 seconds ago");
   }
 
@@ -93,4 +105,111 @@
     assertFormat(5, YEAR_IN_MILLIS, "5 years ago");
     assertFormat(60, YEAR_IN_MILLIS, "60 years ago");
   }
+
+  private static class Constants implements CommonConstants, CommonMessages {
+    @Override
+    public String inTheFuture() {
+      return "in the future";
+    }
+
+    @Override
+    public String month() {
+      return "month";
+    }
+
+    @Override
+    public String months() {
+      return "months";
+    }
+
+    @Override
+    public String year() {
+      return "year";
+    }
+
+    @Override
+    public String years() {
+      return "years";
+    }
+
+    @Override
+    public String oneSecondAgo() {
+      return "1 second ago";
+    }
+
+    @Override
+    public String oneMinuteAgo() {
+      return "1 minute ago";
+    }
+
+    @Override
+    public String oneHourAgo() {
+      return "1 hour ago";
+    }
+
+    @Override
+    public String oneDayAgo() {
+      return "1 day ago";
+    }
+
+    @Override
+    public String oneWeekAgo() {
+      return "1 week ago";
+    }
+
+    @Override
+    public String oneMonthAgo() {
+      return "1 month ago";
+    }
+
+    @Override
+    public String oneYearAgo() {
+      return "1 year ago";
+    }
+
+    @Override
+    public String secondsAgo(long seconds) {
+      return seconds + " seconds ago";
+    }
+
+    @Override
+    public String minutesAgo(long minutes) {
+      return minutes + " minutes ago";
+    }
+
+    @Override
+    public String hoursAgo(long hours) {
+      return hours + " hours ago";
+    }
+
+    @Override
+    public String daysAgo(long days) {
+      return days + " days ago";
+    }
+
+    @Override
+    public String weeksAgo(long weeks) {
+      return weeks + " weeks ago";
+    }
+
+    @Override
+    public String monthsAgo(long months) {
+      return months + " months ago";
+    }
+
+    @Override
+    public String yearsAgo(long years) {
+      return years + " years ago";
+    }
+
+    @Override
+    public String years0MonthsAgo(long years, String yearLabel) {
+      return years + " " + yearLabel + " ago";
+    }
+
+    @Override
+    public String yearsMonthsAgo(long years, String yearLabel, long months, String monthLabel) {
+      return years + " " + yearLabel + ", " + months + " " + monthLabel + " ago";
+    }
+  }
 }