diff --git a/src/WP_CLI/Shell/REPL.php b/src/WP_CLI/Shell/REPL.php
index f0719ca5..cc9ee064 100644
--- a/src/WP_CLI/Shell/REPL.php
+++ b/src/WP_CLI/Shell/REPL.php
@@ -63,6 +63,7 @@ private static function non_expressions() {
 				'global',
 				'unset',
 				'function',
+				'do',
 				'while',
 				'for',
 				'foreach',