diff --git a/hysop/backend/device/codegen/kernels/directional_advection.py b/hysop/backend/device/codegen/kernels/directional_advection.py
index 81210f9b80d606cf82fac38c08275f652af40343..fb0b1cfc4bb3f6346c594985543cc508bdda8384 100644
--- a/hysop/backend/device/codegen/kernels/directional_advection.py
+++ b/hysop/backend/device/codegen/kernels/directional_advection.py
@@ -700,8 +700,8 @@ if __name__ == '__main__':
         min_ghosts=10,
         symbolic_mode=True,
         relative_velocity=0.66,
-        #nparticles=4,                          # MONOLEVEL TEST
-        nparticles=1, is_bilevel=(256,64,32), # BILEVEL TEST
+        nparticles=4,                        # MONOLEVEL TEST
+        #nparticles=1, is_bilevel=(256,64,32), # BILEVEL TEST
         known_vars=dict(
             V_mesh_info=vmesh_info,
             P_mesh_info=pmesh_info,
diff --git a/hysop/backend/device/kernel_autotuner.py b/hysop/backend/device/kernel_autotuner.py
index fb883a10110e1cd07dc34c3fdb522199283a454c..4f09b4c4faa02ee9440848c471e8fe50833736cd 100644
--- a/hysop/backend/device/kernel_autotuner.py
+++ b/hysop/backend/device/kernel_autotuner.py
@@ -200,8 +200,6 @@ class KernelAutotuner(object):
                     msg+='\nMatching cached kernel sources dumped to \'{}\'.'.format(cached_src)
                     msg+='\nCurrently tuned kernel sources dumped to \'{}\'.'.format(tuned_src)
             warnings.warn(msg, CodeGeneratorWarning)
-            import sys
-            sys.exit(0)
             return None
         
         (prg, kernel) = self.build_from_source(kernel_name=kernel_name,
diff --git a/hysop/testsenv.py b/hysop/testsenv.py
index 9ae984c0fbaa43d732efc2c9fa1761f18556a5ae..92ffbb2a6db633b61e8552e245ce8fedfa9ad6ad 100644
--- a/hysop/testsenv.py
+++ b/hysop/testsenv.py
@@ -7,7 +7,9 @@ import contextlib
 import numpy as np
 import sympy as sm
 
-from hysop import __FFTW_ENABLED__, __SCALES_ENABLED__, __ENABLE_LONG_TESTS__, __TEST_ALL_OPENCL_PLATFORMS__
+from hysop import __FFTW_ENABLED__, __SCALES_ENABLED__, __ENABLE_LONG_TESTS__, \
+                  __TEST_ALL_OPENCL_PLATFORMS__, \
+                  __DEFAULT_PLATFORM_ID__, __DEFAULT_DEVICE_ID__
 from hysop.tools.types import check_instance, first_not_None, to_tuple
 from hysop.tools.io_utils import IO
 from hysop.tools.decorators import static_vars
@@ -89,11 +91,17 @@ if __HAS_OPENCL_BACKEND__:
             cl_environments[device_type] = []
             if (device_type is None):
                 mpi_params = default_mpi_params()
-                for i,plat in enumerate(cl.get_platforms()):
-                    for j,dev in enumerate(plat.get_devices()):
-                        cl_env = get_or_create_opencl_env(platform_id=i, device_id=j, 
-                                mpi_params=mpi_params, **kwds)
-                        cl_environments[None].append(cl_env)
+                if all_platforms:
+                    for i,plat in enumerate(cl.get_platforms()):
+                        for j,dev in enumerate(plat.get_devices()):
+                            cl_env = get_or_create_opencl_env(platform_id=i, device_id=j, 
+                                    mpi_params=mpi_params, **kwds)
+                            cl_environments[None].append(cl_env)
+                else:
+                    cl_env = get_or_create_opencl_env(platform_id=__DEFAULT_PLATFORM_ID__, 
+                            device_id=__DEFAULT_DEVICE_ID__, 
+                            mpi_params=mpi_params, **kwds)
+                    cl_environments[None].append(cl_env)
             else:
                 for cl_env in iter_clenv(device_type=None, all_platforms=True):
                     if (cl_env.device.type == device_type):