diff --git a/lib/Interpreter/Virtual/LookbackIterator.php b/lib/Interpreter/Virtual/LookbackIterator.php
index 11562b43..39efc936 100644
--- a/lib/Interpreter/Virtual/LookbackIterator.php
+++ b/lib/Interpreter/Virtual/LookbackIterator.php
@@ -49,7 +49,7 @@ function next() : void {
 	 * Lookback access
 	 */
 
-	function previous() {
+	function previous() : mixed {
 		return $this->previous;
 	}
 }
diff --git a/lib/Interpreter/Virtual/TimestampIterator.php b/lib/Interpreter/Virtual/TimestampIterator.php
index bffbb1fa..ad01ea94 100644
--- a/lib/Interpreter/Virtual/TimestampIterator.php
+++ b/lib/Interpreter/Virtual/TimestampIterator.php
@@ -28,7 +28,7 @@
  */
 class TimestampIterator extends \IteratorIterator {
 	#[\ReturnTypeWillChange]
-	function current() {
+	function current() : mixed {
 		return parent::current()[0];
 	}
 }