diff --git a/tests/hexString.hh b/tests/hexString.hh
index 66dde61..9105f34 100644
--- a/tests/hexString.hh
+++ b/tests/hexString.hh
@@ -22,7 +22,9 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
+#pragma once
 #include <array>
+#include <cstdint>
 #include <string>