diff --git a/dune/solvers/iterationsteps/blockgsstep.cc b/dune/solvers/iterationsteps/blockgsstep.cc
index ab3f3ff4cbd729350da8ea2e78e126f24f1dc9bb..cbb3704684b19fb325f6d4aaac92a49de6ebce7f 100644
--- a/dune/solvers/iterationsteps/blockgsstep.cc
+++ b/dune/solvers/iterationsteps/blockgsstep.cc
@@ -67,7 +67,7 @@ void BlockGSStep<OperatorType, DiscFuncType, BitVectorType>::iterate()
                     for (int k = 0; k < BlockSize; ++k)
 			matRes[j][k] = (k == j);
                 } else 
-                    matRes[j] == mat[i][i][j];
+                    matRes[j] = mat[i][i][j];
 
             }
             matRes.solve(v, r);