diff --git a/Orthtree/include/CGAL/Orthtree.h b/Orthtree/include/CGAL/Orthtree.h
index 1b7b489e4dd..730fb980ca8 100644
--- a/Orthtree/include/CGAL/Orthtree.h
+++ b/Orthtree/include/CGAL/Orthtree.h
@@ -34,6 +34,7 @@
 #include <ostream>
 #include <functional>
 
+#include <bitset>
 #include <stack>
 #include <queue>
 #include <vector>