diff --git a/docopt_value.h b/docopt_value.h
index a923219..2003a7a 100644
--- a/docopt_value.h
+++ b/docopt_value.h
@@ -13,5 +13,6 @@
 #include <vector>
 #include <functional> // std::hash
 #include <iosfwd>
+#include <stdexcept>

 namespace docopt {