diff --git a/src/wp-includes/wp-db.php b/src/wp-includes/wp-db.php
index c49396dc65..0bd7a1882b 100644
--- a/src/wp-includes/wp-db.php
+++ b/src/wp-includes/wp-db.php
@@ -2064,7 +2064,7 @@ class wpdb {
 				}
 			}
 
-			if ( false !== $value['length'] && strlen( $value['value'] ) > $value['length'] ) {
+			if ( false !== $value['length'] && mb_strlen( $value['value'] ) > $value['length'] ) {
 				return false;
 			}
 
diff --git a/tests/phpunit/tests/comment.php b/tests/phpunit/tests/comment.php
index 3905f9f461..dbb01856ab 100644
--- a/tests/phpunit/tests/comment.php
+++ b/tests/phpunit/tests/comment.php
@@ -137,5 +137,12 @@ class Tests_Comment extends WP_UnitTestCase {
 		$id = wp_new_comment( $data );
 
 		$this->assertFalse( $id );
+
+		// Cleanup.
+		if ( isset( $remote_addr ) ) {
+			$_SERVER['REMOTE_ADDR'] = $remote_addr;
+		} else {
+			unset( $_SERVER['REMOTE_ADDR'] );
+		}
 	}
 }