diff --git a/Tests/MaterialLib/TestFluidProperties.cpp b/Tests/MaterialLib/TestFluidProperties.cpp
index f27e4f2f0f414ca9bcf8a2da6b9969599efb863d..ce458140ee0117ee001a90085537f51aa3da269a 100644
--- a/Tests/MaterialLib/TestFluidProperties.cpp
+++ b/Tests/MaterialLib/TestFluidProperties.cpp
@@ -63,8 +63,10 @@ TEST(MaterialFluidProperties, checkPrimaryVariableDependentFluidProperties)
     ASSERT_NEAR(mu_expected,
                 fluid_model->getValue(FluidPropertyType::Viscosity, vars),
                 1.e-10);
+    const double dmu_dT_expected =
+        -1.e-3/368 * std::exp(-(vars[0] - 293) / 368);
     ASSERT_NEAR(
-        -mu_expected,
+        dmu_dT_expected,
         fluid_model->getdValue(FluidPropertyType::Viscosity, vars,
                                MaterialLib::Fluid::PropertyVariableType::T),
         1.e-10);
diff --git a/Tests/MaterialLib/TestFluidViscosity.cpp b/Tests/MaterialLib/TestFluidViscosity.cpp
index 60fa3103b0f4c5c475201dee7a4668ae58789eea..a5a39f97cd4e22f819185a2afeb39539e4c6c700 100644
--- a/Tests/MaterialLib/TestFluidViscosity.cpp
+++ b/Tests/MaterialLib/TestFluidViscosity.cpp
@@ -64,8 +64,10 @@ TEST(Material, checkTemperatureDependentViscosity)
     vars[0] = 350.0;
     const double mu_expected = 1.e-3 * std::exp(-(vars[0] - 293) / 368);
     ASSERT_NEAR(mu_expected, mu->getValue(vars), 1.e-10);
+    const double dmu_dT_expected =
+        -1.e-3/368 * std::exp(-(vars[0] - 293) / 368);
     ASSERT_NEAR(
-        -mu_expected,
+        dmu_dT_expected,
         mu->getdValue(vars, MaterialLib::Fluid::PropertyVariableType::T),
         1.e-10);
 }