diff --up a/include/manifold/mesh.h b/include/manifold/mesh.h
--- a/include/manifold/mesh.h
+++ b/include/manifold/mesh.h
@@ -14,6 +14,7 @@
 #pragma once

 #include <vector>
+#include <istream>

 #include "manifold/common.h"

diff --up a/include/manifold/manifold.h b/include/manifold/manifold.h
--- a/include/manifold/manifold.h
+++ b/include/manifold/manifold.h
@@ -14,6 +14,7 @@
 #include <cstdint>  // uint32_t, uint64_t
 #include <functional>
 #include <memory>  // needed for shared_ptr
+#include <istream>
 #include <mutex>

 #include "manifold/common.h"