diff --git a/libs/pbd/pbd/property_basics.h b/libs/pbd/pbd/property_basics.h
index b5f9f14aff..66c7787b79 100644
--- a/libs/pbd/pbd/property_basics.h
+++ b/libs/pbd/pbd/property_basics.h
@@ -173,6 +173,6 @@ private:
 }
 
 namespace std {
-ostream& operator<< (std::ostream& os, PBD::PropertyChange const & pc);
+	LIBPBD_API ostream& operator<< (std::ostream& os, PBD::PropertyChange const & pc);
 }