diff --git a/09-find_duplicates/cpp/find_duplicates_test.cpp b/09-find_duplicates/cpp/find_duplicates_test.cpp
index 32b00019ab19e38677f3a2d47f878a02b0cf263b..95ced16a00e32b31e8eaa18c1e02f8cb65a2a9e8 100644
--- a/09-find_duplicates/cpp/find_duplicates_test.cpp
+++ b/09-find_duplicates/cpp/find_duplicates_test.cpp
@@ -6,6 +6,7 @@
 #include <vector>
 #include <algorithm>
 #include <type_traits>
+#include <cstdint>
 
 using namespace std;