diff --git a/js/src/irregexp/imported/regexp-code-generator.cc b/js/src/irregexp/imported/regexp-code-generator.cc
--- a/imported/regexp-code-generator.cc
+++ b/imported/regexp-code-generator.cc
@@ -5,6 +5,7 @@
 #include "irregexp/imported/regexp-code-generator.h"

 #include <cstddef>
+#include <iostream>
 #include <tuple>
 #include <type_traits>
 #include <utility>