diff --git a/tests/t00012/t00012.cc b/tests/t00012/t00012.cc
index 4419edc0..5bc5c244 100644
--- a/tests/t00012/t00012.cc
+++ b/tests/t00012/t00012.cc
@@ -1,6 +1,7 @@
 #include <algorithm>
 #include <map>
 #include <numeric>
+#include <string>
 #include <variant>
 
 namespace clanguml {