diff --git a/day4/examples/TSP-pstl/TSP-Itinerary.cc b/day4/examples/TSP-pstl/TSP-Itinerary.cc
index 4aafc842abc5c518097d635d280a0c5651f4d32d..1fcd4d39406682f9ab6c74c7d39ec476968fd8e4 100644
--- a/day4/examples/TSP-pstl/TSP-Itinerary.cc
+++ b/day4/examples/TSP-pstl/TSP-Itinerary.cc
@@ -4,6 +4,7 @@ module;
 #include <numeric>
 #include <algorithm>
 #include <iostream>
+#include <span>
 export module TSP:Itinerary;
 import :Cities;