diff --git a/reframe_tests/base_tests.py b/reframe_tests/base_tests.py
index 43cac73e..43398ff7 100644
--- a/reframe_tests/base_tests.py
+++ b/reframe_tests/base_tests.py
@@ -301,7 +301,7 @@ class GprMaxTaskfarmRegressionTest(GprMaxBScanRegressionTest):
 class GprMaxMPIRegressionTest(GprMaxRegressionTest):
     # TODO: Make this a variable
     serial_dependency: type[GprMaxRegressionTest]
-    mpi_layout = variable(typ.List[int])
+    mpi_layout = parameter()
 
     @run_after("setup", always_last=True)
     def configure_test_run(self):
diff --git a/reframe_tests/reframe_tests.py b/reframe_tests/reframe_tests.py
index 8df81dd5..920749ef 100644
--- a/reframe_tests/reframe_tests.py
+++ b/reframe_tests/reframe_tests.py
@@ -178,7 +178,7 @@ class TestSubgridsWithAntennaModel(GprMaxAPIRegressionTest):
 @rfm.simple_test
 class Test2DModelXYMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "2d", "waveform", "hertzian_dipole"}
-    mpi_layout = [4, 4, 1]
+    mpi_layout = parameter([[4, 4, 1]])
     serial_dependency = Test2DModelXY
     model = serial_dependency.model
 
@@ -186,7 +186,7 @@ class Test2DModelXYMpi(GprMaxMPIRegressionTest):
 @rfm.simple_test
 class Test2DModelXZMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "2d", "waveform", "hertzian_dipole"}
-    mpi_layout = [4, 1, 4]
+    mpi_layout = parameter([[4, 1, 4]])
     serial_dependency = Test2DModelXZ
     model = serial_dependency.model
 
@@ -194,7 +194,7 @@ class Test2DModelXZMpi(GprMaxMPIRegressionTest):
 @rfm.simple_test
 class Test2DModelYZMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "2d", "waveform", "hertzian_dipole"}
-    mpi_layout = [1, 4, 4]
+    mpi_layout = parameter([[1, 4, 4]])
     serial_dependency = Test2DModelYZ
     model = serial_dependency.model
 
@@ -202,7 +202,7 @@ class Test2DModelYZMpi(GprMaxMPIRegressionTest):
 @rfm.simple_test
 class TestHertzianDipoleSourceMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "hertzian_dipole", "waveform"}
-    mpi_layout = [3, 3, 3]
+    mpi_layout = parameter([[3, 3, 3]])
     serial_dependency = TestHertzianDipoleSource
     model = serial_dependency.model
 
@@ -210,7 +210,7 @@ class TestHertzianDipoleSourceMpi(GprMaxMPIRegressionTest):
 @rfm.simple_test
 class TestMagneticDipoleSourceMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "magnetic_dipole", "waveform"}
-    mpi_layout = [3, 3, 3]
+    mpi_layout = parameter([[3, 3, 3]])
     serial_dependency = TestMagneticDipoleSource
     model = serial_dependency.model
 
@@ -218,7 +218,7 @@ class TestMagneticDipoleSourceMpi(GprMaxMPIRegressionTest):
 @rfm.simple_test
 class TestDispersiveMaterialsMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "hertzian_dipole", "waveform", "material", "dispersive", "box"}
-    mpi_layout = [3, 3, 3]
+    mpi_layout = parameter([[3, 3, 3]])
     serial_dependency = TestDispersiveMaterials
     model = serial_dependency.model
 
@@ -226,7 +226,7 @@ class TestDispersiveMaterialsMpi(GprMaxMPIRegressionTest):
 @rfm.simple_test
 class TestTransmissionLineSourceMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "transmission_line", "waveform"}
-    mpi_layout = [3, 3, 3]
+    mpi_layout = parameter([[3, 3, 3]])
     serial_dependency = TestTransmissionLineSource
     model = serial_dependency.model
 
@@ -234,7 +234,7 @@ class TestTransmissionLineSourceMpi(GprMaxMPIRegressionTest):
 @rfm.simple_test
 class TestEdgeGeometryMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "geometry", "edge", "transmission_line", "waveform", "antenna"}
-    mpi_layout = [3, 3, 3]
+    mpi_layout = parameter([[3, 3, 3]])
     serial_dependency = TestEdgeGeometry
     model = serial_dependency.model
     is_antenna_model = True
@@ -261,7 +261,7 @@ class TestBoxGeometryDefaultPml(GprMaxRegressionTest):
 @rfm.simple_test
 class TestBoxGeometryNoPmlMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "geometery", "box"}
-    mpi_layout = [2, 2, 2]
+    mpi_layout = parameter([[2, 2, 2], [3, 3, 3], [4, 4, 4]])
     serial_dependency = TestBoxGeometryNoPml
     model = serial_dependency.model
     sourcesdir = "src/box_geometry_tests"
@@ -274,7 +274,7 @@ class TestBoxGeometryNoPmlMpi(GprMaxMPIRegressionTest):
 @rfm.simple_test
 class TestBoxGeometryDefaultPmlMpi(GprMaxMPIRegressionTest):
     tags = {"test", "mpi", "geometery", "box"}
-    mpi_layout = [2, 2, 2]
+    mpi_layout = parameter([[2, 2, 2], [3, 3, 3], [4, 4, 4]])
     serial_dependency = TestBoxGeometryDefaultPml
     model = serial_dependency.model
     sourcesdir = "src/box_geometry_tests"