diff --git a/MathLib/LinAlg/UnifiedMatrixSetters.cpp b/MathLib/LinAlg/UnifiedMatrixSetters.cpp
index 00dbc7ce0ab9cd56fcb7613ac58b5b9cbfb8fa1b..9cb8b559f3c884cf09b48381fb6499cd6b96c218 100644
--- a/MathLib/LinAlg/UnifiedMatrixSetters.cpp
+++ b/MathLib/LinAlg/UnifiedMatrixSetters.cpp
@@ -82,6 +82,7 @@ void setVector(Eigen::VectorXd& v, MatrixVectorTraits<Eigen::VectorXd>::Index co
 
 // Global PETScMatrix/PETScVector //////////////////////////////////////////
 
+#include <numeric>
 #include "MathLib/LinAlg/PETSc/PETScVector.h"
 #include "MathLib/LinAlg/PETSc/PETScMatrix.h"