Index: src/pingus/prefab_file.hpp
--- src/pingus/prefab_file.hpp.orig
+++ src/pingus/prefab_file.hpp
@@ -18,6 +18,7 @@
 #define HEADER_PINGUS_PINGUS_PREFAB_FILE_HPP
 
 #include <vector>
+#include <string>
 
 #include "util/file_reader.hpp"
 #include "util/pathname.hpp"
