diff --git a/includes/block/DatabaseBlock.php b/includes/block/DatabaseBlock.php
index c73ce9cc1e3..c560866412b 100644
--- a/includes/block/DatabaseBlock.php
+++ b/includes/block/DatabaseBlock.php
@@ -847,7 +847,7 @@ class DatabaseBlock extends AbstractBlock {
 		$autoblock->setTarget( $autoblockIP );
 		$autoblock->setBlocker( $this->getBlocker() );
 		$autoblock->setReason(
-			wfMessage( 'autoblocker', $this->getTarget(), $this->getReasonComment()->text )
+			wfMessage( 'autoblocker', (string)$this->getTarget(), $this->getReasonComment()->text )
 		);
 		$timestamp = wfTimestampNow();
 		$autoblock->setTimestamp( $timestamp );