--- a/3rdparty/fmt/include/fmt/format.h
+++ b/3rdparty/fmt/include/fmt/format.h
@@ -52,6 +52,7 @@
 #    include <memory>  // std::allocator_traits
 #  endif
 #  include <stdexcept>     // std::runtime_error
+#  include <stdlib.h>
 #  include <string>        // std::string
 #  include <system_error>  // std::system_error