diff --git a/include/date/date.h b/include/date/date.h
index 5974fc4..3be91af 100644
--- a/include/date/date.h
+++ b/include/date/date.h
@@ -55,6 +55,7 @@
 #include <iterator>
 #include <limits>
 #include <locale>
+#include <memory>
 #include <ostream>
 #include <ratio>
 #include <sstream>