diff --git a/src/Data.h b/src/Data.h
index a6ab4bf..0f0b062 100644
--- a/src/Data.h
+++ b/src/Data.h
@@ -14,6 +14,7 @@
 #include <set>
 #include <iterator>
 #include <bitset>
+#include <functional>
 
 #include "IndividualDataSet.h"
 #include "Option.h"
diff --git a/src/IndividualDataSet.h b/src/IndividualDataSet.h
index 7a05c3b..0ea5e7c 100644
--- a/src/IndividualDataSet.h
+++ b/src/IndividualDataSet.h
@@ -11,6 +11,7 @@
 #include "GivenKinship.h"
 #include <armadillo>
 #include <list>
+#include <functional>
 
 #include "IndividualData.h"
 #include "Option.h"