diff --git a/run_3d.sh b/run_3d.sh
index c471932..909a2f5 100755
--- a/run_3d.sh
+++ b/run_3d.sh
@@ -7,7 +7,7 @@ set -e
 
 root_dir="$(cd "$(dirname "$0")" && pwd)"
 pffdtd_engine="$root_dir/build/src/cpp/pffdtd-engine"
-pffdtd_engine="$root_dir/cmake-build-sycl/src/cpp/pffdtd-engine"
+pffdtd_engine="$root_dir/cmake-build-cuda/src/cpp/pffdtd-engine"
 
 sim_name="ProStudio"
 sim_setup="${sim_name}.py"
diff --git a/src/cpp/pffdtd/engine_3d_cpu.cpp b/src/cpp/pffdtd/engine_3d_cpu.cpp
index a7840d7..9b784a8 100644
--- a/src/cpp/pffdtd/engine_3d_cpu.cpp
+++ b/src/cpp/pffdtd/engine_3d_cpu.cpp
@@ -78,7 +78,7 @@ auto process_bnl_fd(
   return getTime() - start;
 }
 
-auto run(Simulation3D& sd) -> double {
+auto run(Simulation3D& sd) -> void {
   // keep local ints, scalars
   int64_t const Ns   = sd.Ns;
   int64_t const Nr   = sd.Nr;
@@ -366,12 +366,10 @@ auto run(Simulation3D& sd) -> double {
   fmt::println("Air update: {:.6}s, {:.2} Mvox/s", elapsedAir, Npts * Nt / 1e6 / elapsedAir);
   fmt::println("Boundary loop: {:.6}s, {:.2} Mvox/s", elapsedBn, Nb * Nt / 1e6 / elapsedBn);
   fmt::println("Combined (total): {:.6}s, {:.2} Mvox/s", elapsed, Npts * Nt / 1e6 / elapsed);
-
-  return elapsed;
 }
 
 } // namespace
 
-auto Engine3DCPU::operator()(Simulation3D& sim) const -> double { return run(sim); }
+auto Engine3DCPU::operator()(Simulation3D& sim) const -> void { run(sim); }
 
 } // namespace pffdtd
diff --git a/src/cpp/pffdtd/engine_3d_cpu.hpp b/src/cpp/pffdtd/engine_3d_cpu.hpp
index 6d57416..02ce9f8 100644
--- a/src/cpp/pffdtd/engine_3d_cpu.hpp
+++ b/src/cpp/pffdtd/engine_3d_cpu.hpp
@@ -9,7 +9,7 @@
 namespace pffdtd {
 
 struct Engine3DCPU {
-  auto operator()(Simulation3D& sim) const -> double;
+  auto operator()(Simulation3D& sim) const -> void;
 };
 
 } // namespace pffdtd
diff --git a/src/cpp/pffdtd/engine_3d_cuda.cu b/src/cpp/pffdtd/engine_3d_cuda.cu
index 95d7347..a8b1f9e 100644
--- a/src/cpp/pffdtd/engine_3d_cuda.cu
+++ b/src/cpp/pffdtd/engine_3d_cuda.cu
@@ -680,7 +680,7 @@ void split_data(Simulation3D const* sim, std::span<HostData<Real>> ghds) {
 }
 
 // run the sim!
-static auto run(Simulation3D const& sim) -> double {
+static auto run(Simulation3D const& sim) -> void {
   // if you want to test synchronous, env variable for that
   char const* s = getenv("CUDA_LAUNCH_BLOCKING");
   if (s != nullptr) {
@@ -1357,9 +1357,8 @@ static auto run(Simulation3D const& sim) -> double {
   std::printf("Boundary loop: %.6fs, %.2f Mvox/s\n", elapsedBoundary, sim.Nb * sim.Nt / 1e6 / elapsedBoundary);
   std::printf("Air update: %.6fs, %.2f Mvox/s\n", elapsedAir, sim.Npts * sim.Nt / 1e6 / elapsedAir);
   std::printf("Combined (total): %.6fs, %.2f Mvox/s\n", elapsed, sim.Npts * sim.Nt / 1e6 / elapsed);
-  return elapsed;
 }
 
-auto Engine3DCUDA::operator()(Simulation3D& sim) const -> double { return run(sim); }
+auto Engine3DCUDA::operator()(Simulation3D& sim) const -> void { run(sim); }
 
 } // namespace pffdtd
diff --git a/src/cpp/pffdtd/engine_3d_cuda.hpp b/src/cpp/pffdtd/engine_3d_cuda.hpp
index 58abc49..20e6f78 100644
--- a/src/cpp/pffdtd/engine_3d_cuda.hpp
+++ b/src/cpp/pffdtd/engine_3d_cuda.hpp
@@ -13,7 +13,7 @@
 namespace pffdtd {
 
 struct Engine3DCUDA {
-  auto operator()(Simulation3D& sim) const -> double;
+  auto operator()(Simulation3D& sim) const -> void;
 };
 
 } // namespace pffdtd
diff --git a/src/cpp/pffdtd/engine_3d_sycl.cpp b/src/cpp/pffdtd/engine_3d_sycl.cpp
index 30d4523..d4a4e94 100644
--- a/src/cpp/pffdtd/engine_3d_sycl.cpp
+++ b/src/cpp/pffdtd/engine_3d_sycl.cpp
@@ -11,7 +11,7 @@
 
 namespace pffdtd {
 
-auto Engine3DSYCL::operator()(Simulation3D& sim) const -> double {
+auto Engine3DSYCL::operator()(Simulation3D& sim) const -> void {
   PFFDTD_ASSERT(sim.fcc_flag == 0);
 
   auto queue  = sycl::queue{sycl::property::queue::enable_profiling{}};
@@ -318,10 +318,6 @@ auto Engine3DSYCL::operator()(Simulation3D& sim) const -> double {
   for (auto i{0UL}; i < static_cast<size_t>(Nr * Nt); ++i) {
     sim.u_out[i] = host[i];
   }
-
-  fmt::println("");
-
-  return 0.0;
 }
 
 } // namespace pffdtd
diff --git a/src/cpp/pffdtd/engine_3d_sycl.hpp b/src/cpp/pffdtd/engine_3d_sycl.hpp
index a7fcb05..a372388 100644
--- a/src/cpp/pffdtd/engine_3d_sycl.hpp
+++ b/src/cpp/pffdtd/engine_3d_sycl.hpp
@@ -11,7 +11,7 @@
 namespace pffdtd {
 
 struct Engine3DSYCL {
-  auto operator()(Simulation3D& sim) const -> double;
+  auto operator()(Simulation3D& sim) const -> void;
 };
 
 } // namespace pffdtd