diff --git a/MaterialLib/Fluid/Density/LinearTemperatureDependentDensity.h b/MaterialLib/Fluid/Density/LinearTemperatureDependentDensity.h
index 3d7327d5607c24fed51285689120bc81bbc8d350..dd130b89bb9e3db3d4ad4cbf06008e94fbb80dcd 100644
--- a/MaterialLib/Fluid/Density/LinearTemperatureDependentDensity.h
+++ b/MaterialLib/Fluid/Density/LinearTemperatureDependentDensity.h
@@ -50,7 +50,7 @@ public:
     double getValue(const ArrayType& var_vals) const override
     {
         const double T = var_vals[static_cast<int>(PropertyVariableType::T)];
-        return _rho0 * (1 + _beta * (T - _temperature0));
+        return _rho0 * (1 - _beta * (T - _temperature0));
     }
 
     /// Get the partial differential of the density with respect to temperature.
@@ -62,7 +62,7 @@ public:
     {
         (void)var_vals;
         (void)var;
-        return _rho0 * _beta;
+        return - _rho0 * _beta;
     }
 
 private:
diff --git a/Tests/MaterialLib/TestFluidDensity.cpp b/Tests/MaterialLib/TestFluidDensity.cpp
index 4e592cc3892bd44124b98584abf8ee1752d44aa8..6c0785fd1ba60581c27dea29d5326673ce3a3606 100644
--- a/Tests/MaterialLib/TestFluidDensity.cpp
+++ b/Tests/MaterialLib/TestFluidDensity.cpp
@@ -91,9 +91,9 @@ TEST(Material, checkLinearTemperatureDependentDensity)
 
     ArrayType vars;
     vars[0] = 273.1;
-    ASSERT_NEAR(1000.0 * (1 + 4.3e-4 * (vars[0] - 293.0)), rho->getValue(vars),
+    ASSERT_NEAR(1000.0 * (1 - 4.3e-4 * (vars[0] - 293.0)), rho->getValue(vars),
                 1.e-10);
-    ASSERT_NEAR(1000.0 * 4.3e-4,
+    ASSERT_NEAR(-1000.0 * 4.3e-4,
                 rho->getdValue(vars, Fluid::PropertyVariableType::T), 1.e-10);
 }
 
diff --git a/Tests/MaterialLib/TestFluidProperties.cpp b/Tests/MaterialLib/TestFluidProperties.cpp
index 0cf7851693a87786b96d975468c484bcd117e1ed..e89905b4f9ce962746325ae3780aeee53dc5ce41 100644
--- a/Tests/MaterialLib/TestFluidProperties.cpp
+++ b/Tests/MaterialLib/TestFluidProperties.cpp
@@ -70,10 +70,10 @@ TEST(MaterialFluidProperties, checkPrimaryVariableDependentFluidProperties)
         1.e-10);
 
     vars[0] = 273.1;
-    ASSERT_NEAR(1000.0 * (1 + 4.3e-4 * (vars[0] - 293.0)),
+    ASSERT_NEAR(1000.0 * (1 - 4.3e-4 * (vars[0] - 293.0)),
                 fluid_model->getValue(FluidPropertyType::Density, vars),
                 1.e-10);
-    ASSERT_NEAR(1000.0 * 4.3e-4,
+    ASSERT_NEAR(-1000.0 * 4.3e-4,
                 fluid_model->getdValue(FluidPropertyType::Density, vars,
                                        Fluid::PropertyVariableType::T),
                 1.e-10);
@@ -86,7 +86,7 @@ TEST(MaterialFluidProperties, checkFluidPropertiesWithDensityDependentModels_T)
         "    <density>"
         "        <type>TemperatureDependent</type>"
         "        <temperature0> 293.0 </temperature0> "
-        "        <beta> 2.5003219164466073e-05 </beta> "
+        "        <beta> -2.5003219164466073e-05 </beta> "
         "        <rho0> 998.</rho0>"
         "    </density>"
         "    <viscosity>"