diff --git a/opm/simulators/wells/ParallelWellInfo.hpp b/opm/simulators/wells/ParallelWellInfo.hpp
index 3eeac1b9e..8262d930c 100644
--- a/opm/simulators/wells/ParallelWellInfo.hpp
+++ b/opm/simulators/wells/ParallelWellInfo.hpp
@@ -28,6 +28,7 @@
 #include <opm/simulators/utils/ParallelCommunication.hpp>
 
 #include <memory>
+#include <unordered_map>
 
 namespace Opm {