diff --git a/dpsim-models/src/DP/DP_Ph3_Resistor.cpp b/dpsim-models/src/DP/DP_Ph3_Resistor.cpp
index 2a93eb5306..7ca6a3a828 100644
--- a/dpsim-models/src/DP/DP_Ph3_Resistor.cpp
+++ b/dpsim-models/src/DP/DP_Ph3_Resistor.cpp
@@ -56,7 +56,7 @@ void DP::Ph3::Resistor::mnaCompInitialize(Real omega, Real timeStep,
 
 void DP::Ph3::Resistor::mnaCompApplySystemMatrixStamp(
     SparseMatrixRow &systemMatrix) {
-  MatrixComp conductance = Matrix::Zero(3, 3);
+  MatrixFixedSizeComp<3, 3> conductance = Matrix::Zero(3, 3);
   conductance.real() = (**mResistance).inverse();
 
   MNAStampUtils::stampAdmittanceMatrix(
diff --git a/dpsim-models/src/EMT/EMT_Ph3_Resistor.cpp b/dpsim-models/src/EMT/EMT_Ph3_Resistor.cpp
index d90bd772dd..88ce5229de 100644
--- a/dpsim-models/src/EMT/EMT_Ph3_Resistor.cpp
+++ b/dpsim-models/src/EMT/EMT_Ph3_Resistor.cpp
@@ -69,8 +69,8 @@ void EMT::Ph3::Resistor::mnaCompInitialize(Real omega, Real timeStep,
 
 void EMT::Ph3::Resistor::mnaCompApplySystemMatrixStamp(
     SparseMatrixRow &systemMatrix) {
-  Matrix conductance = Matrix::Zero(3, 3);
-  Math::invertMatrix(**mResistance, conductance);
+  MatrixFixedSize<3, 3> conductance = Matrix::Zero(3, 3);
+  conductance = (**mResistance).inverse();
 
   MNAStampUtils::stampConductanceMatrix(
       conductance, systemMatrix, matrixNodeIndex(0), matrixNodeIndex(1),
diff --git a/dpsim-models/src/SP/SP_Ph3_Resistor.cpp b/dpsim-models/src/SP/SP_Ph3_Resistor.cpp
index 0b1117240e..8c6cebfc59 100644
--- a/dpsim-models/src/SP/SP_Ph3_Resistor.cpp
+++ b/dpsim-models/src/SP/SP_Ph3_Resistor.cpp
@@ -53,7 +53,7 @@ void SP::Ph3::Resistor::mnaCompInitialize(Real omega, Real timeStep,
 
 void SP::Ph3::Resistor::mnaCompApplySystemMatrixStamp(
     SparseMatrixRow &systemMatrix) {
-  MatrixComp conductance = Matrix::Zero(3, 3);
+  MatrixFixedSizeComp<3, 3> conductance = Matrix::Zero(3, 3);
   conductance.real() = (**mResistance).inverse();
 
   MNAStampUtils::stampAdmittanceMatrix(