diff --git a/src/applications/fact/extract/PhabricatorFactUpdateIterator.php b/src/applications/fact/extract/PhabricatorFactUpdateIterator.php
--- a/src/applications/fact/extract/PhabricatorFactUpdateIterator.php
+++ b/src/applications/fact/extract/PhabricatorFactUpdateIterator.php
@@ -33,6 +33,7 @@
     }
   }
 
+  #[\ReturnTypeWillChange]
   public function key() {
     return $this->getCursorFromObject($this->current());
   }
diff --git a/src/applications/harbormaster/storage/build/HarbormasterBuildLogChunkIterator.php b/src/applications/harbormaster/storage/build/HarbormasterBuildLogChunkIterator.php
--- a/src/applications/harbormaster/storage/build/HarbormasterBuildLogChunkIterator.php
+++ b/src/applications/harbormaster/storage/build/HarbormasterBuildLogChunkIterator.php
@@ -18,6 +18,7 @@
     $this->cursor = $this->min;
   }
 
+  #[\ReturnTypeWillChange]
   public function key() {
     return $this->current()->getID();
   }
diff --git a/src/infrastructure/storage/lisk/LiskMigrationIterator.php b/src/infrastructure/storage/lisk/LiskMigrationIterator.php
--- a/src/infrastructure/storage/lisk/LiskMigrationIterator.php
+++ b/src/infrastructure/storage/lisk/LiskMigrationIterator.php
@@ -26,6 +26,7 @@
     $this->cursor = 0;
   }
 
+  #[\ReturnTypeWillChange]
   public function key() {
     return $this->current()->getID();
   }
diff --git a/src/infrastructure/storage/lisk/LiskRawMigrationIterator.php b/src/infrastructure/storage/lisk/LiskRawMigrationIterator.php
--- a/src/infrastructure/storage/lisk/LiskRawMigrationIterator.php
+++ b/src/infrastructure/storage/lisk/LiskRawMigrationIterator.php
@@ -16,6 +16,7 @@
     $this->cursor = 0;
   }
 
+  #[\ReturnTypeWillChange]
   public function key() {
     return idx($this->current(), $this->column);
   }
diff --git a/src/infrastructure/storage/lisk/PhabricatorQueryIterator.php b/src/infrastructure/storage/lisk/PhabricatorQueryIterator.php
--- a/src/infrastructure/storage/lisk/PhabricatorQueryIterator.php
+++ b/src/infrastructure/storage/lisk/PhabricatorQueryIterator.php
@@ -18,6 +18,7 @@
     $this->pager = $pager;
   }
 
+  #[\ReturnTypeWillChange]
   public function key() {
     return $this->current()->getID();
   }