diff --git a/includes/Content/GadgetDefinitionContent.php b/includes/Content/GadgetDefinitionContent.php
index 1f792401..24d02b3f 100644
--- a/includes/Content/GadgetDefinitionContent.php
+++ b/includes/Content/GadgetDefinitionContent.php
@@ -63,7 +63,7 @@ class GadgetDefinitionContent extends JsonContent {
 				$this->validation = $this->getData();
 			} else {
 				$validator = new GadgetDefinitionValidator();
-				$this->validation = $validator->validate( $this->getAssocArray() );
+				$this->validation = $validator->validate( $this->getAssocArray(), true );
 			}
 		}
 		return $this->validation;
@@ -80,7 +80,7 @@ class GadgetDefinitionContent extends JsonContent {
 		$info = wfObjectToArray( $this->getData()->getValue() );
 		/** @var GadgetDefinitionContentHandler $handler */
 		$handler = $this->getContentHandler();
-		$info = wfArrayPlus2d( $info, $handler->getDefaultMetadata() );
+		$info = wfArrayPlus2d( $info, $handler->getEmptyDefinition() );
 
 		return $info;
 	}
diff --git a/includes/Content/GadgetDefinitionContentHandler.php b/includes/Content/GadgetDefinitionContentHandler.php
index 7c4263c2..e4dd3851 100644
--- a/includes/Content/GadgetDefinitionContentHandler.php
+++ b/includes/Content/GadgetDefinitionContentHandler.php
@@ -48,7 +48,19 @@ class GadgetDefinitionContentHandler extends JsonContentHandler {
 
 	public function makeEmptyContent() {
 		$class = $this->getContentClass();
-		return new $class( FormatJson::encode( $this->getDefaultMetadata(), "\t" ) );
+		return new $class( FormatJson::encode( $this->getEmptyDefinition(), "\t" ) );
+	}
+
+	public function getEmptyDefinition() {
+		return [
+			'settings' => [
+				'category' => '',
+			],
+			'module' => [
+				'pages' => [],
+				'dependencies' => [],
+			]
+		];
 	}
 
 	public function getDefaultMetadata() {
@@ -95,22 +107,28 @@ class GadgetDefinitionContentHandler extends JsonContentHandler {
 					$this->makeLink( $parserOutput, $page, $title );
 				}
 			}
-			foreach ( $data->module->dependencies as &$dep ) {
-				if ( str_starts_with( $dep, 'ext.gadget.' ) ) {
-					$gadgetId = explode( 'ext.gadget.', $dep )[1];
-					$title = Title::makeTitleSafe( NS_GADGET_DEFINITION, $gadgetId );
-					$this->makeLink( $parserOutput, $dep, $title );
+			if ( isset( $data->module->dependencies ) ) {
+				foreach ( $data->module->dependencies as &$dep ) {
+					if ( str_starts_with( $dep, 'ext.gadget.' ) ) {
+						$gadgetId = explode( 'ext.gadget.', $dep )[ 1 ];
+						$title = Title::makeTitleSafe( NS_GADGET_DEFINITION, $gadgetId );
+						$this->makeLink( $parserOutput, $dep, $title );
+					}
 				}
 			}
-			foreach ( $data->module->peers as &$peer ) {
-				$title = Title::makeTitleSafe( NS_GADGET_DEFINITION, $peer );
-				$this->makeLink( $parserOutput, $peer, $title );
+			if ( isset( $data->module->peers ) ) {
+				foreach ( $data->module->peers as &$peer ) {
+					$title = Title::makeTitleSafe( NS_GADGET_DEFINITION, $peer );
+					$this->makeLink( $parserOutput, $peer, $title );
+				}
 			}
-			foreach ( $data->module->messages as &$msg ) {
-				$title = Title::makeTitleSafe( NS_MEDIAWIKI, $msg );
-				$this->makeLink( $parserOutput, $msg, $title );
+			if ( isset( $data->module->messages ) ) {
+				foreach ( $data->module->messages as &$msg ) {
+					$title = Title::makeTitleSafe( NS_MEDIAWIKI, $msg );
+					$this->makeLink( $parserOutput, $msg, $title );
+				}
 			}
-			if ( $data->settings->category ) {
+			if ( isset( $data->settings->category ) && $data->settings->category ) {
 				$this->makeLink(
 					$parserOutput,
 					$data->settings->category,
diff --git a/includes/GadgetDefinitionNamespaceRepo.php b/includes/GadgetDefinitionNamespaceRepo.php
index a919c74a..1ca694ba 100644
--- a/includes/GadgetDefinitionNamespaceRepo.php
+++ b/includes/GadgetDefinitionNamespaceRepo.php
@@ -129,7 +129,10 @@ class GadgetDefinitionNamespaceRepo extends GadgetRepo {
 					return null;
 				}
 
-				return Gadget::serializeDefinition( $id, $content->getAssocArray() );
+				$handler = $content->getContentHandler();
+				'@phan-var \MediaWiki\Extension\Gadgets\Content\GadgetDefinitionContentHandler $handler';
+				$data = wfArrayPlus2d( $content->getAssocArray(), $handler->getDefaultMetadata() );
+				return Gadget::serializeDefinition( $id, $data );
 			},
 			[
 				'checkKeys' => [ $key ],
diff --git a/tests/phpunit/integration/GadgetDefinitionContentHandlerTest.php b/tests/phpunit/integration/GadgetDefinitionContentHandlerTest.php
new file mode 100644
index 00000000..fdb38f61
--- /dev/null
+++ b/tests/phpunit/integration/GadgetDefinitionContentHandlerTest.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace phpunit\integration;
+
+use MediaWiki\Revision\RevisionRecord;
+use MediaWiki\Revision\SlotRecord;
+use MediaWikiIntegrationTestCase;
+
+/**
+ * @covers \MediaWiki\Extension\Gadgets\Content\GadgetDefinitionContentHandler
+ * @covers \MediaWiki\Extension\Gadgets\Content\GadgetDefinitionContent
+ * @group Gadgets
+ * @group Database
+ */
+class GadgetDefinitionContentHandlerTest extends MediaWikiIntegrationTestCase {
+
+	public function testHandler() {
+		$status = $this->editPage( 'Gadget definition:X1', '{}' );
+		/** @var RevisionRecord $rev */
+		$rev = $status->getValue()['revision-record'];
+		$revText = $rev->getContent( SlotRecord::MAIN )->serialize();
+		$handler = $this->getServiceContainer()->getContentHandlerFactory()->getContentHandler( 'GadgetDefinition' );
+		$this->assertEquals( $handler->makeEmptyContent()->serialize(), $revText );
+	}
+}