diff --git a/dune/tectonic/minimisation.hh b/dune/tectonic/minimisation.hh
index ef818bdbf1f8e7d5310652d07bb54503c6b43c19..dc509eccd359f4422d9eaef2170e08da0cd10431 100644
--- a/dune/tectonic/minimisation.hh
+++ b/dune/tectonic/minimisation.hh
@@ -37,28 +37,6 @@ void descentMinimisation(Functional const &J,
       2.0 * computeEnergy(J.A, v), JRestb, *J.phi, x, v);
   // }}}
 
-  { // Debug
-    Interval<double> D;
-    JRest.subDiff(0, D);
-
-    dverb
-        << "## Directional derivative (as per subdifferential of restriction): "
-        << D[1] << " (coordinates of the restriction)" << std::endl;
-    /*
-      It is possible that this differs quite a lot from the
-      directional derivative computed in the descentDirection()
-      method:
-
-      If phi is nonsmooth at x, so that the directional
-      derivatives jump, and |x| is computed to be too small or too
-      large globally or locally, the locally computed
-      subdifferential and the globally computed subdifferential
-      will no longer coincide!
-
-      The assertion D[1] <= 0 may thus fail.
-    */
-  }
-
   int count;
   double const stepsize = bisection.minimize(JRest, 0.0, 0.0, count);
   dverb << "Number of iterations in the bisection method: " << count