diff --git a/aiida_lammps/calculations/lammps/base.py b/aiida_lammps/calculations/lammps/base.py
index 2311558..5974073 100644
--- a/aiida_lammps/calculations/lammps/base.py
+++ b/aiida_lammps/calculations/lammps/base.py
@@ -101,11 +101,8 @@ def define(cls, spec):
             valid_type=str,
             default=cls._DEFAULT_RESTART_FILENAME,
         )
-        spec.input(
-            "metadata.options.parser_name",
-            valid_type=str,
-            default=cls._DEFAULT_PARSER,
-        )
+        spec.inputs["metadata"]["options"]["parser_name"].default = cls._DEFAULT_PARSER
+
         spec.output(
             "results",
             valid_type=orm.Dict,
diff --git a/aiida_lammps/calculations/lammps/force.py b/aiida_lammps/calculations/lammps/force.py
index 9a2b784..6d4885a 100644
--- a/aiida_lammps/calculations/lammps/force.py
+++ b/aiida_lammps/calculations/lammps/force.py
@@ -14,11 +14,7 @@ class ForceCalculation(BaseLammpsCalculation):
     def define(cls, spec):
         super().define(spec)
 
-        spec.input(
-            "metadata.options.parser_name",
-            valid_type=str,
-            default="lammps.force",
-        )
+        spec.inputs["metadata"]["options"]["parser_name"].default = "lammps.force"
 
         spec.output(
             "arrays",
diff --git a/aiida_lammps/calculations/lammps/md.py b/aiida_lammps/calculations/lammps/md.py
index d58ef59..d599f9b 100644
--- a/aiida_lammps/calculations/lammps/md.py
+++ b/aiida_lammps/calculations/lammps/md.py
@@ -17,11 +17,7 @@ class MdCalculation(BaseLammpsCalculation):
     def define(cls, spec):
         super().define(spec)
 
-        spec.input(
-            "metadata.options.parser_name",
-            valid_type=str,
-            default="lammps.md",
-        )
+        spec.inputs["metadata"]["options"]["parser_name"].default = "lammps.md"
         spec.default_output_port = "results"
 
         spec.output(
diff --git a/aiida_lammps/calculations/lammps/md_multi.py b/aiida_lammps/calculations/lammps/md_multi.py
index af93b4d..1224b4e 100644
--- a/aiida_lammps/calculations/lammps/md_multi.py
+++ b/aiida_lammps/calculations/lammps/md_multi.py
@@ -16,11 +16,7 @@ class MdMultiCalculation(BaseLammpsCalculation):
     def define(cls, spec):
         super().define(spec)
 
-        spec.input(
-            "metadata.options.parser_name",
-            valid_type=str,
-            default="lammps.md.multi",
-        )
+        spec.inputs["metadata"]["options"]["parser_name"].default = "lammps.md.multi"
         spec.default_output_port = "results"
 
         spec.output_namespace(
diff --git a/aiida_lammps/calculations/lammps/optimize.py b/aiida_lammps/calculations/lammps/optimize.py
index 7544d2c..9edf68a 100644
--- a/aiida_lammps/calculations/lammps/optimize.py
+++ b/aiida_lammps/calculations/lammps/optimize.py
@@ -19,11 +19,7 @@ class OptimizeCalculation(BaseLammpsCalculation):
     def define(cls, spec):
         super().define(spec)
 
-        spec.input(
-            "metadata.options.parser_name",
-            valid_type=str,
-            default="lammps.optimize",
-        )
+        spec.inputs["metadata"]["options"]["parser_name"].default = "lammps.optimize"
 
         spec.output(
             "structure",