diff --git a/dune/solvers/solvers/tcgsolver.cc b/dune/solvers/solvers/tcgsolver.cc
index a24e1406d762a234f4dd121461d1feda39dd7b33..c46f0b6c3e829d2b39392216d49c932e7c868ef6 100644
--- a/dune/solvers/solvers/tcgsolver.cc
+++ b/dune/solvers/solvers/tcgsolver.cc
@@ -235,7 +235,7 @@ void TruncatedCGSolver<MatrixType, VectorType>::solve()
 
         normOfOldCorrection = normOfCorrection;
 
-        if (!isinf(convRate) && !isnan(convRate)) {
+        if (!std::isinf(convRate) && !std::isnan(convRate)) {
             totalConvRate *= convRate;
             this->maxTotalConvRate_ = std::max(this->maxTotalConvRate_, std::pow(totalConvRate, 1/((double)convRateCounter+1)));
             convRateCounter++;