diff --git a/src/library/io_state.cpp b/src/library/io_state.cpp
index bc9a85fa2..a5c8dbf23 100644
--- a/src/library/io_state.cpp
+++ b/src/library/io_state.cpp
@@ -14,6 +14,8 @@ io_state const & get_dummy_ios() {
     return g_dummy_ios;
 }
 
+io_state::io_state():io_state(mk_print_formatter_factory()) {}
+
 io_state::io_state(formatter_factory const & fmtf):
     m_formatter_factory(fmtf),
     m_regular_channel(std::make_shared<stdout_channel>()),
diff --git a/src/library/io_state.h b/src/library/io_state.h
index 6a53b4a90..9efdfa3a7 100644
--- a/src/library/io_state.h
+++ b/src/library/io_state.h
@@ -23,6 +23,7 @@ class io_state {
     std::shared_ptr<output_channel> m_regular_channel;
     std::shared_ptr<output_channel> m_diagnostic_channel;
 public:
+    io_state();
     io_state(formatter_factory const & fmtf);
     io_state(options const & opts, formatter_factory const & fmtf);
     io_state(io_state const & ios, std::shared_ptr<output_channel> const & r, std::shared_ptr<output_channel> const d);