diff --git a/lib/Doctrine/ODM/MongoDB/Iterator/CachingIterator.php b/lib/Doctrine/ODM/MongoDB/Iterator/CachingIterator.php
index 9f8ddcf54a..d726712013 100644
--- a/lib/Doctrine/ODM/MongoDB/Iterator/CachingIterator.php
+++ b/lib/Doctrine/ODM/MongoDB/Iterator/CachingIterator.php
@@ -58,7 +58,9 @@ public function __construct(Traversable $iterator)
     /** @see https://php.net/countable.count */
     public function count(): int
     {
+        $currentKey = key($this->items);
         $this->exhaustIterator();
+        for (reset($this->items); key($this->items) !== $currentKey; next($this->items));
 
         return count($this->items);
     }
diff --git a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/CachingIteratorTest.php b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/CachingIteratorTest.php
index c077cadcb5..52b90c1dec 100644
--- a/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/CachingIteratorTest.php
+++ b/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/CachingIteratorTest.php
@@ -114,7 +114,7 @@ public function testToArrayAfterPartialIteration(): void
     public function testCount(): void
     {
         $iterator = new CachingIterator($this->getTraversable([1, 2, 3]));
-        $this->assertCount(3, $iterator);
+        self::assertCount(3, $iterator);
     }
 
     public function testCountAfterPartialIteration(): void
@@ -122,18 +122,24 @@ public function testCountAfterPartialIteration(): void
         $iterator = new CachingIterator($this->getTraversable([1, 2, 3]));
 
         $iterator->rewind();
-        $this->assertTrue($iterator->valid());
-        $this->assertSame(0, $iterator->key());
-        $this->assertSame(1, $iterator->current());
+        self::assertTrue($iterator->valid());
+        self::assertSame(0, $iterator->key());
+        self::assertSame(1, $iterator->current());
 
         $iterator->next();
-        $this->assertCount(3, $iterator);
+        self::assertSame(1, $iterator->key());
+        self::assertSame(2, $iterator->current());
+
+        self::assertCount(3, $iterator);
+        self::assertTrue($iterator->valid());
+        self::assertSame(1, $iterator->key());
+        self::assertSame(2, $iterator->current());
     }
 
     public function testCountWithEmptySet(): void
     {
         $iterator = new CachingIterator($this->getTraversable([]));
-        $this->assertCount(0, $iterator);
+        self::assertCount(0, $iterator);
     }
 
     /**
@@ -172,7 +178,7 @@ public function rewind(): void
         };
 
         $iterator = new CachingIterator($nestedIterator);
-        $this->assertCount(1, $iterator);
+        self::assertCount(1, $iterator);
     }
 
     /**