diff --git a/projects/jdwp/defs/command_sets/event_request.py b/projects/jdwp/defs/command_sets/event_request.py
index 4b661ee..46c4694 100644
--- a/projects/jdwp/defs/command_sets/event_request.py
+++ b/projects/jdwp/defs/command_sets/event_request.py
@@ -81,20 +81,20 @@
     "Modifier cases",
     TaggedUnion(
         __SetCommand_out_modKind,
-        {
-            ModifierKind.COUNT: CountModifier,
-            ModifierKind.CONDITIONAL: ConditionalModifier,
-            ModifierKind.THREAD_ONLY: ThreadOnlyModifier,
-            ModifierKind.CLASS_ONLY: ClassOnlyModifier,
-            ModifierKind.CLASS_MATCH: ClassMatchModifier,
-            ModifierKind.CLASS_EXCLUDE: ClassExcludeModifier,
-            ModifierKind.STEP: StepModifier,
-            ModifierKind.LOCATION_ONLY: LocationOnlyModifier,
-            ModifierKind.EXCEPTION_ONLY: ExceptionOnlyModifier,
-            ModifierKind.FIELD_ONLY: FieldOnlyModifier,
-            ModifierKind.INSTANCE_ONLY: InstanceOnlyModifier,
-            ModifierKind.SOURCE_NAME_MATCH: SourceNameMatchModifier,
-        },
+        [
+            (ModifierKind.COUNT, CountModifier),
+            (ModifierKind.CONDITIONAL, ConditionalModifier),
+            (ModifierKind.THREAD_ONLY, ThreadOnlyModifier),
+            (ModifierKind.CLASS_ONLY, ClassOnlyModifier),
+            (ModifierKind.CLASS_MATCH, ClassMatchModifier),
+            (ModifierKind.CLASS_EXCLUDE, ClassExcludeModifier),
+            (ModifierKind.STEP, StepModifier),
+            (ModifierKind.LOCATION_ONLY, LocationOnlyModifier),
+            (ModifierKind.EXCEPTION_ONLY, ExceptionOnlyModifier),
+            (ModifierKind.FIELD_ONLY, FieldOnlyModifier),
+            (ModifierKind.INSTANCE_ONLY, InstanceOnlyModifier),
+            (ModifierKind.SOURCE_NAME_MATCH, SourceNameMatchModifier),
+        ],
     ),
     "Modifier cases.",
 )
diff --git a/projects/jdwp/defs/schema.py b/projects/jdwp/defs/schema.py
index 483e6be..2a3c56a 100644
--- a/projects/jdwp/defs/schema.py
+++ b/projects/jdwp/defs/schema.py
@@ -4,7 +4,7 @@
 
 from __future__ import annotations
 from dataclasses import dataclass
-from typing import Optional, Generic, TypeVar, Type as TypeAlias, Union
+from typing import Optional, Generic, Tuple, TypeVar, Type as TypeAlias, Union
 from collections.abc import Mapping
 from enum import Enum
 from collections.abc import Set, Sequence
@@ -85,7 +85,10 @@ class TaggedUnion(Generic[EnumT]):
     """Tagged Union class type"""
 
     tag: Field[UnionTag[EnumT]]
-    cases: Mapping[EnumT, Struct]
+    cases: Sequence[Tuple[EnumT, Struct]]
+
+    def __post_init__(self):
+        object.__setattr__(self, "cases", tuple(self.cases))
 
 
 @dataclass(frozen=True)
@@ -114,6 +117,9 @@ class Struct:
 
     fields: Sequence[Field[Type]]
 
+    def __post_init__(self):
+        object.__setattr__(self, "fields", tuple(self.fields))
+
 
 @dataclass(frozen=True)
 class Command:
@@ -125,6 +131,9 @@ class Command:
     reply: Optional[Struct]
     error: Set[ErrorType]
 
+    def __post_init__(self):
+        object.__setattr__(self, "error", frozenset(self.error))
+
 
 @dataclass(frozen=True)
 class CommandSet:
@@ -133,3 +142,6 @@ class CommandSet:
     name: str
     id: int
     commands: Sequence[Command]
+
+    def __post_init__(self):
+        object.__setattr__(self, "commands", tuple(self.commands))
diff --git a/projects/jdwp/tests/defs/schema.py b/projects/jdwp/tests/defs/schema.py
index d845a45..2701a69 100644
--- a/projects/jdwp/tests/defs/schema.py
+++ b/projects/jdwp/tests/defs/schema.py
@@ -7,9 +7,13 @@ class SchemaTests(unittest.TestCase):
     def test_schema_can_be_imported(self):
         from projects.jdwp.defs.schema import OpaqueType
 
-    def test_command_sets_can_be_imported(self):
+    def test_command_sets_are_hashable(self):
         from projects.jdwp.defs.command_sets import (
             event_request,
             reference_type,
             virtual_machine,
         )
+
+        hash(event_request.EventRequest)
+        hash(reference_type.ReferenceType)
+        hash(event_request.EventRequest)