diff --git a/lib/Recur/RRuleIterator.php b/lib/Recur/RRuleIterator.php
index 0a8f9bcdc..0cd1c0356 100644
--- a/lib/Recur/RRuleIterator.php
+++ b/lib/Recur/RRuleIterator.php
@@ -787,7 +787,10 @@ protected function getMonthlyOccurrences() {
                 } else {
 
                     // if it was negative we count from the end of the array
-                    $byDayResults[] = $dayHits[count($dayHits) + $offset];
+                    // might not exist, fx. -5th tuesday
+                    if (isset($dayHits[count($dayHits) + $offset])) {
+                        $byDayResults[] = $dayHits[count($dayHits) + $offset];
+                    }
                 }
             } else {
                 // There was no counter (first, second, last wednesdays), so we
diff --git a/tests/VObject/Recur/RRuleIteratorTest.php b/tests/VObject/Recur/RRuleIteratorTest.php
index 8299002b0..912293486 100644
--- a/tests/VObject/Recur/RRuleIteratorTest.php
+++ b/tests/VObject/Recur/RRuleIteratorTest.php
@@ -627,6 +627,21 @@ function testIgnoredStuff() {
 
     }
 
+    function testMinusFifthThursday() {
+
+        $this->parse(
+            'FREQ=MONTHLY;BYDAY=-4TH,-5TH;COUNT=4',
+            '2015-01-01 00:15:00',
+            array(
+                '2015-01-01 00:15:00',
+                '2015-01-08 00:15:00',
+                '2015-02-05 00:15:00',
+                '2015-03-05 00:15:00'
+            )
+        );
+
+    }
+
     /**
      * @expectedException InvalidArgumentException
      */