diff --git a/libmpdata++/output/detail/output_common.hpp b/libmpdata++/output/detail/output_common.hpp
index b3258c18..1a7d968d 100644
--- a/libmpdata++/output/detail/output_common.hpp
+++ b/libmpdata++/output/detail/output_common.hpp
@@ -158,7 +158,7 @@ namespace libmpdataxx
               record_time = this->time;
               for (int t = 0; t < outwindow; ++t)
               {
-                if ((this->timestep - t) % static_cast<int>(outfreq) == 0 && this->timestep >= static_cast<int>(outstart)) record_all();
+                if ((this->timestep - t) % static_cast<int>(outfreq) == 0 && (this->timestep - t) >= static_cast<int>(outstart)) record_all();
               }
             }
           }
diff --git a/libmpdata++/output/hdf5.hpp b/libmpdata++/output/hdf5.hpp
index a9e07ae2..a890b45c 100644
--- a/libmpdata++/output/hdf5.hpp
+++ b/libmpdata++/output/hdf5.hpp
@@ -199,18 +199,18 @@ namespace libmpdataxx
             // T
             {
               // incl. t=0 and t=outstart
-              const hsize_t nt_out = this->outstart == 0 ? 
-                (nt - this->outstart) / this->outfreq + 1 :
-                (nt - this->outstart) / this->outfreq + 2;  // for outstart>0 we still want to store t=0
+              const hsize_t nt_out = ((nt - this->outstart) / this->outfreq + 1) * this->outwindow
+                + (this->outstart == 0 ? 0 : 1) // for outstart>0 we still want to store t=0
+                - std::max(0, this->outwindow - int(std::fmod(nt, this->outfreq)) - 1);  // timsteps from outwindow that go beyond nt
 
               float dt = this->dt;
 
               blitz::Array<typename solver_t::real_t, 1> coord(nt_out);
               if(this->outstart == 0)
-                coord(blitz::Range(0,nt_out-1)) = (this->var_dt ? this->outfreq : this->outfreq * this->dt) * (blitz::firstIndex() + this->outstart/this->outfreq);
+                coord(blitz::Range(0,nt_out-1)) = (this->var_dt ? 1 : this->dt) * (floor(blitz::firstIndex() / this->outwindow) * this->outfreq + fmod(blitz::firstIndex(), this->outwindow));
               else
               {
-                coord(blitz::Range(1,nt_out-1)) = (this->var_dt ? this->outfreq : this->outfreq * this->dt) * (blitz::firstIndex() + this->outstart/this->outfreq);
+                coord(blitz::Range(1,nt_out-1)) = (this->var_dt ? 1 : this->dt) * (floor(blitz::firstIndex() / this->outwindow) * this->outfreq + fmod(blitz::firstIndex(), this->outwindow) + this->outstart);
                 coord(0)=0;
               }