diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 8a91d152bf..dad7f15862 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -616,7 +616,7 @@ function maybe_serialize( $data ) {
  */
 function maybe_unserialize( $data ) {
 	if ( is_serialized( $data ) ) { // Don't attempt to unserialize data that wasn't serialized going in.
-		return @unserialize( $data );
+		return @unserialize( trim( $data ) );
 	}
 
 	return $data;
diff --git a/tests/phpunit/tests/functions.php b/tests/phpunit/tests/functions.php
index c00439d092..db691131ed 100644
--- a/tests/phpunit/tests/functions.php
+++ b/tests/phpunit/tests/functions.php
@@ -291,6 +291,7 @@ class Tests_Functions extends WP_UnitTestCase {
 				),
 				true,
 			),
+			array( '   s:25:"this string is serialized";   ', true ),
 		);
 	}