diff --git a/Mf2/Parser.php b/Mf2/Parser.php
index 1ba275f..de4abd0 100644
--- a/Mf2/Parser.php
+++ b/Mf2/Parser.php
@@ -238,6 +238,26 @@ function convertTimeFormat($time) {
 	}
 }
 
+/**
+ * Normalize an ordinal date to YYYY-MM-DD
+ * This function should only be called after validating the $dtValue
+ * matches regex \d{4}-\d{2}
+ * @param string $dtValue
+ * @return string
+ */
+function normalizeOrdinalDate($dtValue) {
+	list($year, $day) = explode('-', $dtValue, 2);
+	$day = intval($day);
+	if ($day < 367 && $day > 0) {
+		$date = \DateTime::createFromFormat('Y-z', $dtValue);
+		$date->modify('-1 day'); # 'z' format is zero-based so need to adjust
+		if ($date->format('Y') === $year) {
+			return $date->format('Y-m-d');
+		}
+	}
+	return '';
+}
+
 /**
  * If a date value has a timezone offset, normalize it.
  * @param string $dtValue
@@ -711,6 +731,9 @@ public function parseDT(\DOMElement $dt, &$dates = array(), &$impliedTimezone =
 					// Is the current part a valid date AND no other date representation has been found?
 					} elseif (preg_match('/^\d{4}-\d{2}-\d{2}$/', $part) and empty($datePart)) {
 						$datePart = $part;
+					// Is the current part a valid ordinal date AND no other date representation has been found?
+					} elseif (preg_match('/^\d{4}-\d{3}$/', $part) and empty($datePart)) {
+						$datePart = normalizeOrdinalDate($part);
 					// Is the current part a valid timezone offset AND no other timezone part has been found?
 					} elseif (preg_match('/^(Z|[+-]\d{1,2}:?(\d{2})?)$/', $part) and empty($timezonePart)) {
 						$timezonePart = $part;
diff --git a/tests/Mf2/ParseDTTest.php b/tests/Mf2/ParseDTTest.php
index 6aabc44..fb917d6 100644
--- a/tests/Mf2/ParseDTTest.php
+++ b/tests/Mf2/ParseDTTest.php
@@ -531,5 +531,24 @@ public function testDtWithoutYear() {
 		$this->assertEquals('--12-28', $output['items'][0]['properties']['bday'][0]);
 	}
 
+	/**
+	 * @see https://github.com/indieweb/php-mf2/issues/167
+	 * @see https://github.com/microformats/mf2py/blob/master/test/examples/datetimes.html
+	 */
+	public function testNormalizeOrdinalDate() {
+		$input = '<div class="h-event">
+	<h1 class="p-name">Ordinal date</h1>
+	<p> When:
+		<span class="dt-start">
+			<span class="value">2016-062</span>
+			<span class="value">12:30AM</span>
+			(UTC<span class="value">-06:00</span>)
+	</p>
+</div>';
+		$parser = new Parser($input);
+		$output = $parser->parse();
+
+		$this->assertEquals('2016-03-02 12:30-0600', $output['items'][0]['properties']['start'][0]);
+	}
 }
 
diff --git a/tests/Mf2/ParserTest.php b/tests/Mf2/ParserTest.php
index 4a3cb2a..c238608 100644
--- a/tests/Mf2/ParserTest.php
+++ b/tests/Mf2/ParserTest.php
@@ -823,5 +823,18 @@ public function testNotMutatingPassedInDOM() {
 		Mf2\parse($inputDoc, 'http://snarfed.org/2013-10-23_oauth-dropins');
 		$this->assertEquals($refDoc, $inputDoc, 'Parsing mutated the DOMDocument.');
 	}
+
+	/**
+	 * Make sure day of year passed to normalizeOrdinalDate() is valid
+	 * @see https://github.com/indieweb/php-mf2/issues/167
+	 */
+	public function testInvalidOrdinalDate() {
+		# 365 days in non-leap years
+		$this->assertEquals('2018-12-31', Mf2\normalizeOrdinalDate('2018-365'));
+		$this->assertEquals('', Mf2\normalizeOrdinalDate('2018-366'));
+		# 366 days in leap years
+		$this->assertEquals('2016-12-31', Mf2\normalizeOrdinalDate('2016-366'));
+		$this->assertEquals('', Mf2\normalizeOrdinalDate('2016-367'));
+	}
 }