diff --git a/qt/qt6_natvis/main.cpp b/qt/qt6_natvis/main.cpp
index aa06faf..03c3468 100644
--- a/qt/qt6_natvis/main.cpp
+++ b/qt/qt6_natvis/main.cpp
@@ -10,6 +10,7 @@
 #include <QtCore>
 
 #include <unordered_set>
+#include <unordered_map>
 
 int main(int argc, char *argv[])
 {