diff --git a/modcc/msparse.hpp b/modcc/msparse.hpp
index c7868764e93861d7d49bbb25b91ee3ecaa7cd573..2af48cd53bb471b60bb80074f09c1b5dacdd203d 100644
--- a/modcc/msparse.hpp
+++ b/modcc/msparse.hpp
@@ -7,6 +7,7 @@
 #include <initializer_list>
 #include <iterator>
 #include <stdexcept>
+#include <string>
 #include <vector>
 
 namespace msparse {