diff --git a/Post/PViewDataGModel.cpp b/Post/PViewDataGModel.cpp
index 96fadd77b9a2f1d0a9a2c225422e1980890775fd..65c305c83de0f7d3e2fa35be265772231d5d0bc1 100644
--- a/Post/PViewDataGModel.cpp
+++ b/Post/PViewDataGModel.cpp
@@ -152,6 +152,9 @@ bool PViewDataGModel::finalize(bool computeMinMax, const std::string &interpolat
         }
         else if(it->second.size() == 4){
           // use provided matrices for field and geometry
+          Msg::Warning("You should not specify the geometrical interpolation "
+                       "in ElementNodeData: the geometry is completely determined "
+                       "by the mesh element type. This feature will be removed");
           setInterpolationMatrices(it->first, *it->second[0], *it->second[1],
                                    *it->second[2], *it->second[3]);
         }
diff --git a/doc/texinfo/gmsh.texi b/doc/texinfo/gmsh.texi
index c2852a79ee0e6c0f10b97f0b5bf0d8e9d50b2da0..507f0510a21c48378398b229abd74b53564423b5 100644
--- a/doc/texinfo/gmsh.texi
+++ b/doc/texinfo/gmsh.texi
@@ -3779,10 +3779,10 @@ for prisms, 8 for hexahedra, 9 for polygons and 10 for polyhedra.
 
 @item @var{number-of-interpolation-matrices} 
 is the number of interpolation matrices provided for this element
-topology. Currently you should provide either 2 or 4 matrices: the
-matrices have the same meaning as in @ref{Post-processing commands}.
-The matrices are specified by 2 integers (@var{num-rows} and
-@var{num-columns}) followed by the values.
+topology. Currently you should provide 2 matrices, i.e., the matrices
+that specify how to interpolate the data (they have the same meaning as
+in @ref{Post-processing commands}).  The matrices are specified by 2
+integers (@var{num-rows} and @var{num-columns}) followed by the values.
 
 @end table