diff --git a/ProcessLib/HydroMechanics/HydroMechanicsProcessData.h b/ProcessLib/HydroMechanics/HydroMechanicsProcessData.h
index 122f981e8f715530cdc6cf6ad66d723548b1fce1..ac5618a6b1d17ce1bc3863410648f4616a8aba8a 100644
--- a/ProcessLib/HydroMechanics/HydroMechanicsProcessData.h
+++ b/ProcessLib/HydroMechanics/HydroMechanicsProcessData.h
@@ -10,8 +10,15 @@
 #pragma once
 
 #include <Eigen/Dense>
-#include <utility>
 
+namespace MaterialLib
+{
+namespace Solids
+{
+template <int DisplacementDim>
+struct MechanicsBase;
+}
+}
 namespace ProcessLib
 {
 namespace HydroMechanics