diff --git a/MaterialLib/MPL/Properties/Density/WaterVapourDensity.cpp b/MaterialLib/MPL/Properties/Density/WaterVapourDensity.cpp
index a2c535db6f798f713a834b1efd33091a912219a8..682d208767b44a89d9ee4786b1ff4fad811aaf97 100644
--- a/MaterialLib/MPL/Properties/Density/WaterVapourDensity.cpp
+++ b/MaterialLib/MPL/Properties/Density/WaterVapourDensity.cpp
@@ -46,7 +46,9 @@ PropertyDataType WaterVapourDensity::value(
 {
     double const p = variable_array.liquid_phase_pressure;
     double const T = variable_array.temperature;
+    assert(T >= 273.);
     double const water_density = variable_array.density;
+    assert(water_density > 0.);
 
     return humidity(T, p, water_density) * saturatedVaporDensity(T);
 }
@@ -58,7 +60,9 @@ PropertyDataType WaterVapourDensity::dValue(
 {
     double const p = variable_array.liquid_phase_pressure;
     double const T = variable_array.temperature;
+    assert(T >= 273.);
     double const water_density = variable_array.density;
+    assert(water_density > 0.);
 
     if (variable == Variable::temperature)
     {
diff --git a/MaterialLib/MPL/Properties/Density/WaterVapourDensity.h b/MaterialLib/MPL/Properties/Density/WaterVapourDensity.h
index e545b5b423ca467f8206c90e2e535e7474ec9aa3..953033a1f2a0edfdef0d7dfc86e6f584b68cbc93 100644
--- a/MaterialLib/MPL/Properties/Density/WaterVapourDensity.h
+++ b/MaterialLib/MPL/Properties/Density/WaterVapourDensity.h
@@ -49,6 +49,9 @@ class Phase;
  *   equation are multiplied with \f$1-S\f$ with \f$ S \f$, the water
  * saturation. Therefore the application of the water vapour density model is
  * naturally restricted in the unsaturated zones.
+ *
+ * \note The temperature must be greater then the freezing temperature. In the
+ * paper the offset is 273K, not 273.15 which might cause small inconsistencies.
  */
 class WaterVapourDensity final : public Property
 {