diff --git a/MaterialLib/SolidModels/Ehlers-impl.h b/MaterialLib/SolidModels/Ehlers-impl.h
index 6de8c1b2e27112ea558637f2ace488f4783b3486..48abe75b5852764f2440392d7d93145e55a54e1e 100644
--- a/MaterialLib/SolidModels/Ehlers-impl.h
+++ b/MaterialLib/SolidModels/Ehlers-impl.h
@@ -43,10 +43,12 @@ namespace Solids
 {
 namespace Ehlers
 {
-
-/// Special product of \p v with itself: \f$v \odot v\f$.
-/// v is given in \p Kelvin mapping.
+/// Special product of \c v with itself: \f$v \odot v\f$.
+/// The tensor \c v is given in Kelvin mapping.
 /// \note Implementation only for 2 and 3 dimensions.
+/// \attention Pay attention to the sign of the result, which normally would be
+/// negative, but the returned value is not negated. This has to do with \f$
+/// d(A^{-1})/dA = -A^{-1} \odot A^{-1} \f$.
 template <int DisplacementDim>
 ProcessLib::KelvinMatrixType<DisplacementDim> sOdotS(
     ProcessLib::KelvinVectorType<DisplacementDim> const& v);