diff --git a/unsupported/Eigen/CXX11/ThreadPool b/unsupported/Eigen/CXX11/ThreadPool
index 613fdb57a..7a795da3d 100644
--- a/unsupported/Eigen/CXX11/ThreadPool
+++ b/unsupported/Eigen/CXX11/ThreadPool
@@ -43,6 +43,7 @@
 #include <mutex>
 #include <thread>
 #include <functional>
+#include <memory>
 #include <utility>
 #include "src/util/CXX11Meta.h"
 #include "src/util/MaxSizeVector.h"