diff --git a/src/RRule.php b/src/RRule.php
index cf35b05..d4eddfc 100755
--- a/src/RRule.php
+++ b/src/RRule.php
@@ -1419,6 +1419,7 @@ class RRule implements RRuleInterface
 			}
 			// echo "Cache used up with occurrences remaining\n";
 			if ( $dtstart ) {
+				$dtstart = clone $dtstart; // since DateTime is not immutable, avoid any problem
 				// so we skip the last occurrence of the cache
 				if ( $this->freq === self::SECONDLY ) {
 					$dtstart->modify('+'.$this->interval.'second');
@@ -1628,7 +1629,11 @@ class RRule implements RRuleInterface
 			else {
 				// normal loop, without BYSETPOS
 				while ( ($yearday = current($dayset)) !== false ) {
-					$occurrence = \DateTime::createFromFormat('Y z', "$year $yearday",$this->dtstart->getTimezone());
+					$occurrence = \DateTime::createFromFormat(
+						'Y z',
+						"$year $yearday",
+						$this->dtstart->getTimezone()
+					);
 
 					while ( ($time = current($timeset)) !== false ) {
 						$occurrence->setTime($time[0], $time[1], $time[2]);
diff --git a/src/RSet.php b/src/RSet.php
index 31bee4d..3e047f3 100755
--- a/src/RSet.php
+++ b/src/RSet.php
@@ -204,13 +204,13 @@ class RSet implements RRuleInterface
 
 	public function offsetExists($offset)
 	{
-	throw new \Exception(__METHOD__.' is unimplemented');
-		// return is_numeric($offset) && $offset >= 0 && $offset < count($this);
+		return is_numeric($offset) && $offset >= 0 && $offset < count($this);
 	}
 
 	public function offsetGet($offset)
 	{
-		throw new \Exception(__METHOD__.' is unimplemented');
+		// TODO: Cache
+
 		// if ( isset($this->cache[$offset]) ) {
 		// 	// found in cache
 		// 	return $this->cache[$offset];
@@ -220,30 +220,28 @@ class RSet implements RRuleInterface
 		// 	return null;
 		// }
 
-		// // not in cache and cache not complete, we have to loop to find it
-		// $i = 0;
-		// foreach ( $this as $occurrence ) {
-		// 	if ( $i == $offset ) {
-		// 		return $occurrence;
-		// 	}
-		// 	$i++;
-		// 	if ( $i > $offset ) {
-		// 		break;
-		// 	}
-		// }
-		// return null;
+		// not in cache and cache not complete, we have to loop to find it
+		$i = 0;
+		foreach ( $this as $occurrence ) {
+			if ( $i == $offset ) {
+				return $occurrence;
+			}
+			$i++;
+			if ( $i > $offset ) {
+				break;
+			}
+		}
+		return null;
 	}
 
 	public function offsetSet($offset, $value)
 	{
-		throw new \Exception(__METHOD__.' is unimplemented');
-		// throw new \LogicException('Setting a Date in a RRule is not supported');
+		throw new \LogicException('Setting a Date in a RSet is not supported (use addDate)');
 	}
 
 	public function offsetUnset($offset)
 	{
-		throw new \Exception(__METHOD__.' is unimplemented');
-		// throw new \LogicException('Unsetting a Date in a RRule is not supported');
+		throw new \LogicException('Unsetting a Date in a RSet is not supported (use addDate)');
 	}
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -257,16 +255,15 @@ class RSet implements RRuleInterface
 	 */
 	public function count()
 	{
-		throw new \Exception(__METHOD__.' is unimplemented');
-		// if ( ! $this->count && ! $this->until ) {
-		// 	throw new \LogicException('Cannot count an infinite recurrence rule.');
-		// }
+		if ( $this->isInfinite() ) {
+			throw new \LogicException('Cannot count an infinite recurrence set.');
+		}
 
-		// if ( $this->total === null ) {
-		// 	foreach ( $this as $occurrence ) {}
-		// }
+		if ( $this->total === null ) {
+			foreach ( $this as $occurrence ) {}
+		}
 
-		// return $this->total;
+		return $this->total;
 	}
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/tests/RRuleTest.php b/tests/RRuleTest.php
index 6cf4b0c..1db6efc 100755
--- a/tests/RRuleTest.php
+++ b/tests/RRuleTest.php
@@ -4,39 +4,6 @@ use RRule\RRule;
 
 class RRuleTest extends PHPUnit_Framework_TestCase
 {
-	public function testIsFinite()
-	{
-		$rrule = new RRule(array(
-			'freq' => 'yearly'
-		));
-		$this->assertTrue($rrule->isInfinite());
-		$this->assertFalse($rrule->isFinite());
-
-		$rrule = new RRule(array(
-			'freq' => 'yearly',
-			'count' => 10
-		));
-		$this->assertFalse($rrule->isInfinite());
-		$this->assertTrue($rrule->isFinite());
-	}
-
-	public function testIsLeapYear()
-	{
-		$this->assertFalse(\RRule\is_leap_year(1700));
-		$this->assertFalse(\RRule\is_leap_year(1800));
-		$this->assertFalse(\RRule\is_leap_year(1900));
-		$this->assertTrue(\RRule\is_leap_year(2000));
-	}
-
-	public function testCountable()
-	{
-		$rrule = new RRule(array(
-			'freq' => 'yearly',
-			'count' => 10
-		));
-		$this->assertEquals(10, count($rrule));
-	}
-
 	/**
 	 * These rules are invalid according to the RFC
 	 */
@@ -1724,4 +1691,65 @@ class RRuleTest extends PHPUnit_Framework_TestCase
 		$this->assertEquals(date_create('1997-09-01 09:00:00', new DateTimeZone('America/New_York')), $rrule[0]);
 	}
 
+	public function testIsFinite()
+	{
+		$rrule = new RRule(array(
+			'freq' => 'yearly'
+		));
+		$this->assertTrue($rrule->isInfinite());
+		$this->assertFalse($rrule->isFinite());
+
+		$rrule = new RRule(array(
+			'freq' => 'yearly',
+			'count' => 10
+		));
+		$this->assertFalse($rrule->isInfinite());
+		$this->assertTrue($rrule->isFinite());
+	}
+
+	public function testIsLeapYear()
+	{
+		$this->assertFalse(\RRule\is_leap_year(1700));
+		$this->assertFalse(\RRule\is_leap_year(1800));
+		$this->assertFalse(\RRule\is_leap_year(1900));
+		$this->assertTrue(\RRule\is_leap_year(2000));
+	}
+
+	public function testCountable()
+	{
+		$rrule = new RRule(array(
+			'freq' => 'yearly',
+			'count' => 10
+		));
+		$this->assertEquals(10, count($rrule));
+	}
+
+	public function testOffsetExists()
+	{
+		$rrule = new RRule(array(
+			'freq' => 'daily',
+			'count' => 3,
+			'byday' => 'TU,TH',
+			'dtstart' => '2007-01-01'
+		));
+		$this->assertTrue(isset($rrule[0]));
+		$this->assertTrue(isset($rrule[1]));
+		$this->assertTrue(isset($rrule[2]));
+		$this->assertFalse(isset($rrule[3]));
+	}
+
+	public function testOffsetGet()
+	{
+		$rrule = new RRule(array(
+			'freq' => 'daily',
+			'count' => 3,
+			'byday' => 'TU,TH',
+			'dtstart' => '2007-01-01'
+		));
+
+		$this->assertEquals(date_create('2007-01-02'), $rrule[0]);
+		$this->assertEquals(date_create('2007-01-04'), $rrule[1]);
+		$this->assertEquals(date_create('2007-01-09'), $rrule[2]);
+		$this->assertEquals(null, $rrule[4]);
+	}
 }
diff --git a/tests/RSetTest.php b/tests/RSetTest.php
index 7bcfd12..36ce34b 100755
--- a/tests/RSetTest.php
+++ b/tests/RSetTest.php
@@ -115,7 +115,57 @@ class RSetTest extends PHPUnit_Framework_TestCase
 
 	public function testCountable()
 	{
-		// TODO
+		$rset = new RSet();
+		$rset->addRRule(array(
+			'FREQ' => 'YEARLY',
+			'COUNT' => 6,
+			'BYDAY' => 'TU, TH',
+			'DTSTART' => date_create('1997-09-02 09:00')
+		));
+		$rset->addExdate('1997-09-04 09:00:00');
+		$rset->addExdate('1997-09-11 09:00:00');
+		$rset->addExdate('1997-09-18 09:00:00');
+
+		$this->assertEquals(3, count($rset));
+	}
+
+	public function testOffsetExists()
+	{
+		$rset = new RSet();
+		$rset->addRRule(array(
+			'FREQ' => 'YEARLY',
+			'COUNT' => 6,
+			'BYDAY' => 'TU, TH',
+			'DTSTART' => date_create('1997-09-02 09:00')
+		));
+		$rset->addExdate('1997-09-04 09:00:00');
+		$rset->addExdate('1997-09-11 09:00:00');
+		$rset->addExdate('1997-09-18 09:00:00');
+
+		$this->assertTrue(isset($rset[0]));
+		$this->assertTrue(isset($rset[1]));
+		$this->assertTrue(isset($rset[2]));
+		$this->assertFalse(isset($rset[3]));
+	}
+
+	public function testOffsetGet()
+	{
+		$rset = new RSet();
+		$rset->addRRule(array(
+			'FREQ' => 'YEARLY',
+			'COUNT' => 6,
+			'BYDAY' => 'TU, TH',
+			'DTSTART' => date_create('1997-09-02 09:00:00')
+		));
+		$rset->addExdate('1997-09-04 09:00:00');
+		$rset->addExdate('1997-09-11 09:00:00');
+		$rset->addExdate('1997-09-18 09:00:00');
+
+// var_dump($rset->getOccurrences());
+		$this->assertEquals(date_create('1997-09-02 09:00:00'), $rset[0]);
+		$this->assertEquals(date_create('1997-09-09 09:00:00'), $rset[1]);
+		$this->assertEquals(date_create('1997-09-16 09:00:00'), $rset[2]);
+		$this->assertEquals(null, $rset[3]);
 	}
 
 	public function testRSetInRset()