diff --git a/src/RRule.php b/src/RRule.php
index ad57b06..c9eb5d3 100755
--- a/src/RRule.php
+++ b/src/RRule.php
@@ -519,11 +519,17 @@ class RRule implements RRuleInterface
 	 * Format a rule according to RFC 5545
 	 * @return string
 	 */
-	public function rfcString()
+	public function rfcString($include_timezone = true)
 	{
 		$str = '';
 		if ( $this->rule['DTSTART'] ) {
-			if ( $this->dtstart->getTimeZone()->getName() == 'Z' ) {
+			if ( ! $include_timezone ) {
+				$str = sprintf(
+					"DTSTART:%s\nRRULE:",
+					$this->dtstart->format('Ymd\THis')
+				);
+			}
+			elseif ( $this->dtstart->getTimeZone()->getName() == 'Z' ) {
 				$str = sprintf(
 					"DTSTART:%s\nRRULE:",
 					$this->dtstart->format('Ymd\THis\Z')
@@ -550,10 +556,18 @@ class RRule implements RRuleInterface
 				continue;
 			}
 			if ( $key === 'UNTIL' && $value ) {
-				// according to the RFC, UNTIL must be in UTC
-				$tmp = clone $this->until;
-				$tmp->setTimezone(new \DateTimeZone('UTC'));
-				$parts[] = 'UNTIL='.$tmp->format('Ymd\THis\Z');
+				if ( ! $include_timezone ) {
+					$tmp = clone $this->until;
+					// put until on the same timezone as DTSTART
+					$tmp->setTimeZone($this->dtstart->getTimezone());
+					$parts[] = 'UNTIL='.$tmp->format('Ymd\THis');
+				}
+				else {
+					// according to the RFC, UNTIL must be in UTC
+					$tmp = clone $this->until;
+					$tmp->setTimezone(new \DateTimeZone('UTC'));
+					$parts[] = 'UNTIL='.$tmp->format('Ymd\THis\Z');
+				}
 				continue;
 			}
 			if ( $value ) {
diff --git a/tests/RRuleTest.php b/tests/RRuleTest.php
index 1f571ed..ab0e8b2 100755
--- a/tests/RRuleTest.php
+++ b/tests/RRuleTest.php
@@ -1786,6 +1786,29 @@ class RRuleTest extends PHPUnit_Framework_TestCase
 		$this->assertEquals("DTSTART:19970512T090000Z\nRRULE:FREQ=YEARLY", $rule->rfcString());
 	}
 
+	public function rfcStringsWithoutTimezone()
+	{
+		return array(
+			array(
+				"DTSTART;TZID=America/New_York:19970901T090000\nRRULE:FREQ=DAILY",
+				"DTSTART:19970901T090000\nRRULE:FREQ=DAILY",
+			),
+			array(
+				"DTSTART;TZID=Europe/Paris:19970901T090000\nRRULE:FREQ=DAILY;UNTIL=19970902T070000Z",
+				"DTSTART:19970901T090000\nRRULE:FREQ=DAILY;UNTIL=19970902T090000",
+			),
+		);
+	}
+
+	/**
+	 * @dataProvider rfcStringsWithoutTimezone
+	 */
+	public function testRfcStringWithoutTimezone($str, $expected_str)
+	{
+		$rule = new RRule($str);
+		$this->assertEquals($expected_str, $rule->rfcString(false));
+	}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Timezone