diff --git a/aiida/orm/computers.py b/aiida/orm/computers.py
index f93f958efc..5a8b3b0c5d 100644
--- a/aiida/orm/computers.py
+++ b/aiida/orm/computers.py
@@ -241,6 +241,7 @@ def validate(self) -> None:
         self._transport_type_validator(self.transport_type)
         self._scheduler_type_validator(self.scheduler_type)
         self._workdir_validator(self.get_workdir())
+        self.default_memory_per_machine_validator(self.get_default_memory_per_machine())
 
         try:
             mpirun_cmd = self.get_mpirun_command()
@@ -267,6 +268,9 @@ def _default_mpiprocs_per_machine_validator(cls, def_cpus_per_machine: Optional[
     @classmethod
     def default_memory_per_machine_validator(cls, def_memory_per_machine: Optional[int]) -> None:
         """Validates the default amount of memory (kB) per machine (node)"""
+        if def_memory_per_machine is None:
+            return
+
         if not isinstance(def_memory_per_machine, int) or def_memory_per_machine <= 0:
             raise exceptions.ValidationError(
                 f'Invalid value for def_memory_per_machine, must be a positive int, got: {def_memory_per_machine}'
diff --git a/aiida/orm/utils/builders/computer.py b/aiida/orm/utils/builders/computer.py
index aab594c499..4a63b8e206 100644
--- a/aiida/orm/utils/builders/computer.py
+++ b/aiida/orm/utils/builders/computer.py
@@ -8,8 +8,8 @@
 # For further information please visit http://www.aiida.net               #
 ###########################################################################
 """Manage computer objects with lazy loading of the db env"""
-
 from aiida.cmdline.utils.decorators import with_dbenv
+from aiida.common.exceptions import ValidationError
 from aiida.common.utils import ErrorAccumulator
 
 
@@ -101,22 +101,17 @@ def new(self):
             computer.set_default_mpiprocs_per_machine(mpiprocs_per_machine)
 
         def_memory_per_machine = self._get_and_count('default_memory_per_machine', used)
-        if def_memory_per_machine == 0:
-            def_memory_per_machine = None
-        # In the command line, 0 means unspecified
         if def_memory_per_machine is not None:
             try:
                 def_memory_per_machine = int(def_memory_per_machine)
             except ValueError:
                 raise self.ComputerValidationError(
-                    'Invalid value provided for memory_per_machine, '
-                    'must be a valid integer'
-                )
-            if def_memory_per_machine <= 0:
-                raise self.ComputerValidationError(
-                    'Invalid value provided for default_memory_per_machine, must be positive'
+                    'Invalid value provided for memory_per_machine, must be a valid integer'
                 )
-            computer.set_default_memory_per_machine(def_memory_per_machine)
+            try:
+                computer.set_default_memory_per_machine(def_memory_per_machine)
+            except ValidationError as exception:
+                raise self.ComputerValidationError(f'Invalid value for `default_memory_per_machine`: {exception}')
 
         mpirun_command_internal = self._get_and_count('mpirun_command', used).strip().split(' ')
         if mpirun_command_internal == ['']:
diff --git a/tests/cmdline/commands/test_computer.py b/tests/cmdline/commands/test_computer.py
index 20b46b5787..8ba75ccc54 100644
--- a/tests/cmdline/commands/test_computer.py
+++ b/tests/cmdline/commands/test_computer.py
@@ -7,7 +7,7 @@
 # For further information on the license, see the LICENSE.txt file        #
 # For further information please visit http://www.aiida.net               #
 ###########################################################################
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,invalid-name
 """Tests for the 'verdi computer' command."""
 from collections import OrderedDict
 import os
@@ -89,7 +89,7 @@ def generate_setup_options(ordereddict):
     return options
 
 
-def generate_setup_options_interactive(ordereddict):  # pylint: disable=invalid-name
+def generate_setup_options_interactive(ordereddict):
     """
     Given an (ordered) dict, returns a list of options
 
@@ -181,7 +181,6 @@ def test_noninteractive(run_cli_command, aiida_localhost, non_interactive_editor
 
     result = run_cli_command(computer_setup, options)
 
-    assert result.exception is None, result.output[-1000:]
     new_computer = orm.Computer.objects.get(label=options_dict['label'])
     assert isinstance(new_computer, orm.Computer)
 
@@ -198,22 +197,19 @@ def test_noninteractive(run_cli_command, aiida_localhost, non_interactive_editor
     assert new_computer.get_append_text() == options_dict['append-text']
 
     # Test that I cannot generate twice a computer with the same label
-    result = run_cli_command(computer_setup, options, catch_exceptions=False)
-    assert isinstance(result.exception, SystemExit)
+    result = run_cli_command(computer_setup, options, raises=True)
     assert 'already exists' in result.output
 
 
 @pytest.mark.usefixtures('clear_database_before_test')
-def test_noninteractive_optional_default_mpiprocs(run_cli_command):  # pylint: disable=invalid-name
+def test_noninteractive_optional_default_mpiprocs(run_cli_command):
     """
     Check that if is ok not to specify mpiprocs-per-machine
     """
     options_dict = generate_setup_options_dict({'label': 'computer_default_mpiprocs'})
     options_dict.pop('mpiprocs-per-machine')
     options = generate_setup_options(options_dict)
-    result = run_cli_command(computer_setup, options, catch_exceptions=False)
-
-    assert result.exception is None, result.output[-1000:]
+    run_cli_command(computer_setup, options, catch_exceptions=False)
 
     new_computer = orm.Computer.objects.get(label=options_dict['label'])
     assert isinstance(new_computer, orm.Computer)
@@ -221,16 +217,14 @@ def test_noninteractive_optional_default_mpiprocs(run_cli_command):  # pylint: d
 
 
 @pytest.mark.usefixtures('clear_database_before_test')
-def test_noninteractive_optional_default_mpiprocs_2(run_cli_command):  # pylint: disable=invalid-name
+def test_noninteractive_optional_default_mpiprocs_2(run_cli_command):
     """
     Check that if is the specified value is zero, it means unspecified
     """
     options_dict = generate_setup_options_dict({'label': 'computer_default_mpiprocs_2'})
     options_dict['mpiprocs-per-machine'] = 0
     options = generate_setup_options(options_dict)
-    result = run_cli_command(computer_setup, options, catch_exceptions=False)
-
-    assert result.exception is None, result.output[-1000:]
+    run_cli_command(computer_setup, options, catch_exceptions=False)
 
     new_computer = orm.Computer.objects.get(label=options_dict['label'])
     assert isinstance(new_computer, orm.Computer)
@@ -238,46 +232,40 @@ def test_noninteractive_optional_default_mpiprocs_2(run_cli_command):  # pylint:
 
 
 @pytest.mark.usefixtures('clear_database_before_test')
-def test_noninteractive_optional_default_mpiprocs_3(run_cli_command):  # pylint: disable=invalid-name
+def test_noninteractive_optional_default_mpiprocs_3(run_cli_command):
     """
     Check that it fails for a negative number of mpiprocs
     """
     options_dict = generate_setup_options_dict({'label': 'computer_default_mpiprocs_3'})
     options_dict['mpiprocs-per-machine'] = -1
     options = generate_setup_options(options_dict)
-    result = run_cli_command(computer_setup, options, catch_exceptions=False)
-
-    assert isinstance(result.exception, SystemExit)
+    result = run_cli_command(computer_setup, options, raises=True)
     assert 'mpiprocs_per_machine, must be positive' in result.output
 
 
-def test_noninteractive_optional_default_memory(run_cli_command):  # pylint: disable=invalid-name
+def test_noninteractive_optional_default_memory(run_cli_command):
     """
     Check that if is ok not to specify default-memory-per-machine
     """
     options_dict = generate_setup_options_dict({'label': 'computer_default_mem'})
     options_dict.pop('default-memory-per-machine')
     options = generate_setup_options(options_dict)
-    result = run_cli_command(computer_setup, options)
-
-    assert result.exception is None, result.output[-1000:]
+    run_cli_command(computer_setup, options)
 
     new_computer = orm.Computer.objects.get(label=options_dict['label'])
     assert isinstance(new_computer, orm.Computer)
     assert new_computer.get_default_memory_per_machine() is None
 
 
-def test_noninteractive_optional_default_mem_2(run_cli_command):  # pylint: disable=invalid-name
+def test_noninteractive_optional_default_memory_invalid(run_cli_command):
     """
-    Check that it fails for a negative number of default_memory
+    Check that it fails for a negative number of default_memory.
     """
     options_dict = generate_setup_options_dict({'label': 'computer_default_memory_3'})
     options_dict['default-memory-per-machine'] = -1
     options = generate_setup_options(options_dict)
-    result = run_cli_command(computer_setup, options, catch_exceptions=False)
-
-    assert isinstance(result.exception, SystemExit)
-    assert 'default_memory_per_machine, must be positive' in result.output
+    result = run_cli_command(computer_setup, options, raises=True)
+    assert 'Invalid value for def_memory_per_machine, must be a positive int, got: -1' in result.output
 
 
 @pytest.mark.usefixtures('clear_database_before_test')
@@ -288,8 +276,7 @@ def test_noninteractive_wrong_transport_fail(run_cli_command):
     options_dict = generate_setup_options_dict(replace_args={'label': 'fail_computer'})
     options_dict['transport'] = 'unknown_transport'
     options = generate_setup_options(options_dict)
-    result = run_cli_command(computer_setup, options, catch_exceptions=False)
-    assert isinstance(result.exception, SystemExit)
+    result = run_cli_command(computer_setup, options, raises=True)
     assert "entry point 'unknown_transport' is not valid" in result.output
 
 
@@ -301,9 +288,7 @@ def test_noninteractive_wrong_scheduler_fail(run_cli_command):
     options_dict = generate_setup_options_dict(replace_args={'label': 'fail_computer'})
     options_dict['scheduler'] = 'unknown_scheduler'
     options = generate_setup_options(options_dict)
-    result = run_cli_command(computer_setup, options, catch_exceptions=False)
-
-    assert isinstance(result.exception, SystemExit)
+    result = run_cli_command(computer_setup, options, raises=True)
     assert "entry point 'unknown_scheduler' is not valid" in result.output
 
 
@@ -315,9 +300,7 @@ def test_noninteractive_invalid_shebang_fail(run_cli_command):
     options_dict = generate_setup_options_dict(replace_args={'label': 'fail_computer'})
     options_dict['shebang'] = '/bin/bash'  # Missing #! in front
     options = generate_setup_options(options_dict)
-    result = run_cli_command(computer_setup, options, catch_exceptions=False)
-
-    assert isinstance(result.exception, SystemExit)
+    result = run_cli_command(computer_setup, options, raises=True)
     assert 'The shebang line should start with' in result.output
 
 
@@ -371,7 +354,7 @@ def setUp(self):
         self.comp_builder.prepend_text = ''
         self.comp_builder.append_text = ''
         self.comp_builder.mpiprocs_per_machine = 8
-        self.comp_builder.default_memory_per_machine = 0
+        self.comp_builder.default_memory_per_machine = 100000
         self.comp_builder.mpirun_command = 'mpirun'
         self.comp_builder.shebang = '#!xonsh'