diff --git a/src/Mod/Fem/femsolver/calculix/write_femelement_material.py b/src/Mod/Fem/femsolver/calculix/write_femelement_material.py
index ac930b1a43..1b08ce23ec 100644
--- a/src/Mod/Fem/femsolver/calculix/write_femelement_material.py
+++ b/src/Mod/Fem/femsolver/calculix/write_femelement_material.py
@@ -81,9 +81,12 @@ def write_femelement_material(f, ccxwriter):
             if mat_obj.Category == "Solid":
                 TEC = FreeCAD.Units.Quantity(mat_obj.Material["ThermalExpansionCoefficient"])
                 TEC_in_mmK = TEC.getValueAs("mm/mm/K").Value
-                RT = FreeCAD.Units.Quantity(
-                    mat_obj.Material["ThermalExpansionReferenceTemperature"]
-                )
+                if "ThermalExpansionReferenceTemperature" in mat_obj.Material:
+                    RT = FreeCAD.Units.Quantity(
+                        mat_obj.Material["ThermalExpansionReferenceTemperature"]
+                    )
+                else:
+                    RT = FreeCAD.Units.Quantity("0 K")
                 RT_in_K = RT.getValueAs("K").Value
             elif mat_obj.Category == "Fluid":
                 KV = FreeCAD.Units.Quantity(mat_obj.Material["KinematicViscosity"])