diff --git a/src/PeriodCollection.php b/src/PeriodCollection.php
index eded01a..21922ec 100644
--- a/src/PeriodCollection.php
+++ b/src/PeriodCollection.php
@@ -134,7 +134,7 @@ public function filter(Closure $closure): static
     {
         $collection = clone $this;
 
-        $collection->periods = array_filter($collection->periods, $closure);
+        $collection->periods = array_values(array_filter($collection->periods, $closure));
 
         return $collection;
     }
diff --git a/tests/PeriodCollectionTest.php b/tests/PeriodCollectionTest.php
index b742599..33f396a 100644
--- a/tests/PeriodCollectionTest.php
+++ b/tests/PeriodCollectionTest.php
@@ -277,4 +277,25 @@ public function filter()
         $this->assertCount(1, $filtered);
         $this->assertTrue($filtered[0]->equals($collection[0]));
     }
+
+    /** @test */
+    public function it_loops_after_filter()
+    {
+        $collection = new PeriodCollection(
+            Period::make('2018-01-01', '2018-01-02'),
+            Period::make('2018-01-10', '2018-01-15'),
+            Period::make('2018-01-20', '2018-01-25'),
+            Period::make('2018-01-30', '2018-01-31')
+        );
+
+        $filtered = $collection->filter(function (Period $period) {
+            return $period->length() > 2;
+        });
+
+        $items = [];
+        foreach ($filtered as $item) {
+            $items[] = $item;
+        }
+        $this->assertEquals($filtered->count(), count($items));
+    }
 }