Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/document/Revision.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/document/Revision.java	(revision 1562394)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/document/Revision.java	(working copy)
@@ -161,14 +161,15 @@
     }
     
     /**
-     * Get the difference between two timestamps (a - b) in milliseconds.
+     * Get the timestamp difference between two revisions (r1 - r2) in
+     * milliseconds.
      * 
-     * @param a the first timestamp
-     * @param b the second timestamp
+     * @param r1 the first revision
+     * @param r2 the second revision
      * @return the difference in milliseconds
      */
-    public static long getTimestampDifference(long a, long b) {
-        return a - b;
+    public static long getTimestampDifference(Revision r1, Revision r2) {
+        return r1.getTimestamp() - r2.getTimestamp();
     }
     
     public static Revision fromString(String rev) {
Index: oak-core/src/test/java/org/apache/jackrabbit/oak/plugins/document/RevisionTest.java
===================================================================
--- oak-core/src/test/java/org/apache/jackrabbit/oak/plugins/document/RevisionTest.java	(revision 1562394)
+++ oak-core/src/test/java/org/apache/jackrabbit/oak/plugins/document/RevisionTest.java	(working copy)
@@ -44,15 +44,20 @@
     
     @Test
     public void difference() throws InterruptedException {
+        long t0 = Revision.getCurrentTimestamp();
         Revision r0 = Revision.newRevision(0);
         Revision r1 = Revision.newRevision(0);
-        long timestamp = Revision.getCurrentTimestamp();
-        assertTrue(Revision.getTimestampDifference(r1.getTimestamp(), r0.getTimestamp()) < 10);
-        assertTrue(Revision.getTimestampDifference(timestamp, r0.getTimestamp()) < 10);
-        Thread.sleep(2);
+        long t1 = Revision.getCurrentTimestamp();
+        // the difference must not be more than t1 - t0
+        assertTrue(Revision.getTimestampDifference(r1, r0) <= (t1 - t0));
+        // busy wait until we have a timestamp different from t1
+        long t2;
+        do {
+            t2 = Revision.getCurrentTimestamp();
+        } while (t1 == t2);
+
         Revision r2 = Revision.newRevision(0);
-        assertTrue(Revision.getTimestampDifference(r2.getTimestamp(), r0.getTimestamp()) > 0);
-        assertTrue(Revision.getTimestampDifference(r2.getTimestamp(), r0.getTimestamp()) < 20);
+        assertTrue(Revision.getTimestampDifference(r2, r1) > 0);
     }
     
     @Test