diff --git a/src/PhpSpreadsheet/Collection/Memory/SimpleCache1.php b/src/PhpSpreadsheet/Collection/Memory/SimpleCache1.php
index b8918c915..58463ebea 100644
--- a/src/PhpSpreadsheet/Collection/Memory/SimpleCache1.php
+++ b/src/PhpSpreadsheet/Collection/Memory/SimpleCache1.php
@@ -9,6 +9,11 @@ use Psr\SimpleCache\CacheInterface;
  *
  * Alternative implementation should leverage off-memory, non-volatile storage
  * to reduce overall memory usage.
+ *
+ * Either SimpleCache1 or SimpleCache3, but not both, may be used.
+ * For code coverage testing, it will always be SimpleCache3.
+ *
+ * @codeCoverageIgnore
  */
 class SimpleCache1 implements CacheInterface
 {
diff --git a/src/PhpSpreadsheet/Writer/ZipStream2.php b/src/PhpSpreadsheet/Writer/ZipStream2.php
index ed21a7e39..e03e1d0cf 100644
--- a/src/PhpSpreadsheet/Writer/ZipStream2.php
+++ b/src/PhpSpreadsheet/Writer/ZipStream2.php
@@ -5,6 +5,12 @@ namespace PhpOffice\PhpSpreadsheet\Writer;
 use ZipStream\Option\Archive;
 use ZipStream\ZipStream;
 
+/**
+ * Either ZipStream2 or ZipStream3, but not both, may be used.
+ * For code coverage testing, it will always be ZipStream3.
+ *
+ * @codeCoverageIgnore
+ */
 class ZipStream2
 {
     /**