diff --git a/src/children/XHPChildDeclarationConsistencyValidation.hack b/src/children/XHPChildDeclarationConsistencyValidation.hack
index 9a016b50..8010ed4e 100644
--- a/src/children/XHPChildDeclarationConsistencyValidation.hack
+++ b/src/children/XHPChildDeclarationConsistencyValidation.hack
@@ -11,7 +11,7 @@ use namespace \Facebook\XHP\ChildValidation as XHPChild;
 
 /** Verify that a new child declaration matches the legacy codegen. */
 trait XHPChildDeclarationConsistencyValidation {
-  require extends :x:element;
+  require extends :x:composable-element;
 
   abstract protected static function getChildrenDeclaration(
   ): XHPChild\Constraint;
diff --git a/src/children/XHPChildValidation.hack b/src/children/XHPChildValidation.hack
index b2c73537..a27b438a 100644
--- a/src/children/XHPChildValidation.hack
+++ b/src/children/XHPChildValidation.hack
@@ -11,7 +11,7 @@ use namespace \Facebook\XHP\ChildValidation as XHPChild;
 
 /** Verify that a new child declaration matches the legacy codegen. */
 trait XHPChildValidation {
-  require extends :x:element;
+  require extends :x:composable-element;
 
   abstract protected static function getChildrenDeclaration(
   ): XHPChild\Constraint;