diff --git a/src/Domain/ValueObject/TimeSpan.php b/src/Domain/ValueObject/TimeSpan.php
index a781ac63..c963fbea 100644
--- a/src/Domain/ValueObject/TimeSpan.php
+++ b/src/Domain/ValueObject/TimeSpan.php
@@ -14,15 +14,15 @@
 final class TimeSpan extends Occurrence
 {
     private DateTime $begin;
-    private DateTime $end;
+    private ?DateTime $end;
 
-    public function __construct(DateTime $begin, DateTime $end)
+    public function __construct(DateTime $begin, ?DateTime $end = null)
     {
         $this->begin = $begin;
         $this->end = $end;
     }
 
-    public static function create(DateTime $begin, DateTime $end): self
+    public static function create(DateTime $begin, ?DateTime $end = null): self
     {
         return new static($begin, $end);
     }
@@ -32,7 +32,7 @@ public function getBegin(): DateTime
         return $this->begin;
     }
 
-    public function getEnd(): DateTime
+    public function getEnd(): ?DateTime
     {
         return $this->end;
     }
diff --git a/src/Presentation/Factory/EventFactory.php b/src/Presentation/Factory/EventFactory.php
index 2f834b2a..e93bd640 100644
--- a/src/Presentation/Factory/EventFactory.php
+++ b/src/Presentation/Factory/EventFactory.php
@@ -176,7 +176,9 @@ private function getOccurrenceProperties(Occurrence $occurrence): Generator
 
         if ($occurrence instanceof TimeSpan) {
             yield $this->dateTimeFactory->createProperty('DTSTART', $occurrence->getBegin());
-            yield $this->dateTimeFactory->createProperty('DTEND', $occurrence->getEnd());
+            if ($occurrence->getEnd() !== null) {
+                yield $this->dateTimeFactory->createProperty('DTEND', $occurrence->getEnd());
+            }
         }
     }