diff --git a/triqs/gfs/imtime.hpp b/triqs/gfs/imtime.hpp
index 3bd3f959..a78345d3 100644
--- a/triqs/gfs/imtime.hpp
+++ b/triqs/gfs/imtime.hpp
@@ -77,15 +77,14 @@ namespace triqs { namespace gfs {
     double beta = g->mesh().domain().beta;
     int p = std::floor(tau/beta);
     tau -= p*beta;
-    double a = tau/g->mesh().delta();
-    long n = std::floor(a);
-    double w = a-n;
-    assert(n < g->mesh().size()-1);
-    auto _ = arrays::ellipsis();
+    size_t n; double w; bool in;
+    std::tie(in, n, w) = windowing(g->mesh(),tau);
+    if (!in) TRIQS_RUNTIME_ERROR <<" Evaluation out of bounds";
+    auto gg = on_mesh(*g);
     if ((g->mesh().domain().statistic == Fermion) && (p%2==1))
-     _tmp = - w*g->data()(n, _) - (1-w)*g->data()(n+1, _);
+     _tmp = - (1-w)*gg(n) - w*gg(n+1);
     else
-     _tmp =   w*g->data()(n, _) + (1-w)*g->data()(n+1, _);
+     _tmp =   (1-w)*gg(n) + w*gg(n+1);
     //else { // Speed test to redo when incoparated qview in main branch
     // _tmp(0,0) =   w*g->data()(n, 0,0) + (1-w)*g->data()(n+1, 0,0);
     // _tmp(0,1) =   w*g->data()(n, 0,1) + (1-w)*g->data()(n+1, 0,1);
diff --git a/triqs/gfs/meshes/linear.hpp b/triqs/gfs/meshes/linear.hpp
index b2256764..d75834cc 100644
--- a/triqs/gfs/meshes/linear.hpp
+++ b/triqs/gfs/meshes/linear.hpp
@@ -193,7 +193,7 @@ namespace triqs { namespace gfs {
  template<typename D>
   std::tuple<bool, size_t, double>  windowing ( linear_mesh<D> const & mesh, typename D::point_t const & x) { 
    double a = (x - mesh.x_min())/mesh.delta();
-   long i = floor(a);
+   long i = std::floor(a);
    bool in = (! ((i<0) || (i>long(mesh.size())-1)));
    double w = a-i;
    //   std::cerr  << " window "<< i << " "<< in << "  "<< w<< std::endl ;