diff --git a/includes/Feed/AtomFeed.php b/includes/Feed/AtomFeed.php
index 453943a39f7..5f9af7af398 100644
--- a/includes/Feed/AtomFeed.php
+++ b/includes/Feed/AtomFeed.php
@@ -100,7 +100,7 @@ class AtomFeed extends ChannelFeed {
 			"url" => $this->xmlEncode(
 				$this->urlUtils->expand( $item->getUrlUnescaped(), PROTO_CURRENT ) ?? ''
 			),
-			"date" => $this->xmlEncode( $this->formatTime( $item->getDate() ) ),
+			"date" => $this->xmlEncodeNullable( $this->formatTime( $item->getDate() ) ),
 			"description" => $item->getDescription(),
 			"author" => $item->getAuthor()
 		];
diff --git a/includes/Feed/FeedItem.php b/includes/Feed/FeedItem.php
index a67420afafc..93dd364fa15 100644
--- a/includes/Feed/FeedItem.php
+++ b/includes/Feed/FeedItem.php
@@ -100,6 +100,15 @@ class FeedItem {
 		return htmlspecialchars( $string );
 	}
 
+	/**
+	 * Encode $string so that it can be safely embedded in a XML document,
+	 * returning `null` if $string was `null`.
+	 * @since 1.44
+	 */
+	public function xmlEncodeNullable( ?string $string ): ?string {
+		return $string !== null ? $this->xmlEncode( $string ) : null;
+	}
+
 	/**
 	 * Get the unique id of this item; already xml-encoded
 	 *
diff --git a/includes/Feed/RSSFeed.php b/includes/Feed/RSSFeed.php
index d19e54ca7e2..8ef86d6d580 100644
--- a/includes/Feed/RSSFeed.php
+++ b/includes/Feed/RSSFeed.php
@@ -78,7 +78,7 @@ class RSSFeed extends ChannelFeed {
 			"permalink" => $item->rssIsPermalink,
 			"uniqueID" => $item->getUniqueID(),
 			"description" => $item->getDescription(),
-			"date" => $this->xmlEncode( $this->formatTime( $item->getDate() ) ),
+			"date" => $this->xmlEncodeNullable( $this->formatTime( $item->getDate() ) ),
 			"author" => $item->getAuthor()
 		];
 		$comments = $item->getCommentsUnescaped();