diff --git a/ProcessLib/HeatConduction/HeatConductionFEM.h b/ProcessLib/HeatConduction/HeatConductionFEM.h
index 96994733b56c15363c6bfb09db786d6a4e73b875..de3bfe2d7e3aed8409f13f3931fa0c6794eb29e6 100644
--- a/ProcessLib/HeatConduction/HeatConductionFEM.h
+++ b/ProcessLib/HeatConduction/HeatConductionFEM.h
@@ -70,7 +70,9 @@ public:
           _integration_method(integration_order),
           _shape_matrices(initShapeMatrices<ShapeFunction, ShapeMatricesType,
                                             IntegrationMethod, GlobalDim>(
-              element, is_axially_symmetric, _integration_method))
+              element, is_axially_symmetric, _integration_method)),
+          _heat_fluxes(GlobalDim,
+              std::vector<double>(_integration_method.getNumberOfPoints()))
     {
         // This assertion is valid only if all nodal d.o.f. use the same shape
         // matrices.
@@ -161,9 +163,7 @@ private:
     IntegrationMethod const _integration_method;
     std::vector<ShapeMatrices> _shape_matrices;
 
-    std::vector<std::vector<double>> _heat_fluxes =
-        std::vector<std::vector<double>>(
-            GlobalDim, std::vector<double>(ShapeFunction::NPOINTS));
+    std::vector<std::vector<double>> _heat_fluxes;
 };
 
 }  // namespace HeatConduction