diff --git a/Sources/_OpenAPIGeneratorCore/Translator/RequestBody/translateRequestBody.swift b/Sources/_OpenAPIGeneratorCore/Translator/RequestBody/translateRequestBody.swift
index c109ed67..041a9e00 100644
--- a/Sources/_OpenAPIGeneratorCore/Translator/RequestBody/translateRequestBody.swift
+++ b/Sources/_OpenAPIGeneratorCore/Translator/RequestBody/translateRequestBody.swift
@@ -150,6 +150,7 @@ extension TypesFileTranslator {
         members: [Declaration]
     ) -> Declaration {
         let bodyEnumDecl: Declaration = .enum(
+            isFrozen: true,
             accessModifier: config.access,
             name: typeName.shortSwiftName,
             conformances: Constants.Operation.Output.conformances,
diff --git a/Sources/_OpenAPIGeneratorCore/Translator/Responses/translateResponse.swift b/Sources/_OpenAPIGeneratorCore/Translator/Responses/translateResponse.swift
index 6bc80c7b..8bbd1666 100644
--- a/Sources/_OpenAPIGeneratorCore/Translator/Responses/translateResponse.swift
+++ b/Sources/_OpenAPIGeneratorCore/Translator/Responses/translateResponse.swift
@@ -83,6 +83,7 @@ extension TypesFileTranslator {
         }
         let hasNoContent: Bool = bodyCases.isEmpty
         let contentEnumDecl: Declaration = .enum(
+            isFrozen: true,
             accessModifier: config.access,
             name: bodyTypeName.shortSwiftName,
             conformances: Constants.Operation.Body.conformances,
diff --git a/Sources/_OpenAPIGeneratorCore/Translator/TypesTranslator/translateOperations.swift b/Sources/_OpenAPIGeneratorCore/Translator/TypesTranslator/translateOperations.swift
index deb6e15a..43e0470a 100644
--- a/Sources/_OpenAPIGeneratorCore/Translator/TypesTranslator/translateOperations.swift
+++ b/Sources/_OpenAPIGeneratorCore/Translator/TypesTranslator/translateOperations.swift
@@ -161,6 +161,7 @@ extension TypesFileTranslator {
         }
 
         let enumDecl: Declaration = .enum(
+            isFrozen: true,
             accessModifier: config.access,
             name: outputTypeName.shortSwiftName,
             conformances: Constants.Operation.Output.conformances,
diff --git a/Tests/OpenAPIGeneratorReferenceTests/Resources/ReferenceSources/Petstore/Types.swift b/Tests/OpenAPIGeneratorReferenceTests/Resources/ReferenceSources/Petstore/Types.swift
index a510aad7..27391c43 100644
--- a/Tests/OpenAPIGeneratorReferenceTests/Resources/ReferenceSources/Petstore/Types.swift
+++ b/Tests/OpenAPIGeneratorReferenceTests/Resources/ReferenceSources/Petstore/Types.swift
@@ -616,7 +616,7 @@ public enum Components {
     }
     /// Types generated from the `#/components/requestBodies` section of the OpenAPI document.
     public enum RequestBodies {
-        public enum UpdatePetRequest: Sendable, Equatable, Hashable {
+        @frozen public enum UpdatePetRequest: Sendable, Equatable, Hashable {
             /// - Remark: Generated from `#/components/requestBodies/UpdatePetRequest/json`.
             public struct jsonPayload: Codable, Equatable, Hashable, Sendable {
                 /// - Remark: Generated from `#/components/requestBodies/UpdatePetRequest/json/name`.
@@ -662,7 +662,7 @@ public enum Components {
             }
             /// Received HTTP response headers
             public var headers: Components.Responses.ErrorBadRequest.Headers
-            public enum Body: Sendable, Equatable, Hashable {
+            @frozen public enum Body: Sendable, Equatable, Hashable {
                 /// - Remark: Generated from `#/components/responses/ErrorBadRequest/json`.
                 public struct jsonPayload: Codable, Equatable, Hashable, Sendable {
                     /// - Remark: Generated from `#/components/responses/ErrorBadRequest/json/code`.
@@ -819,7 +819,7 @@ public enum Operations {
                 public init() {}
             }
             public var cookies: Operations.listPets.Input.Cookies
-            public enum Body: Sendable, Equatable, Hashable {}
+            @frozen public enum Body: Sendable, Equatable, Hashable {}
             public var body: Operations.listPets.Input.Body?
             /// Creates a new `Input`.
             ///
@@ -843,7 +843,7 @@ public enum Operations {
                 self.body = body
             }
         }
-        public enum Output: Sendable, Equatable, Hashable {
+        @frozen public enum Output: Sendable, Equatable, Hashable {
             public struct Ok: Sendable, Equatable, Hashable {
                 public struct Headers: Sendable, Equatable, Hashable {
                     public var My_Response_UUID: Swift.String
@@ -863,7 +863,7 @@ public enum Operations {
                 }
                 /// Received HTTP response headers
                 public var headers: Operations.listPets.Output.Ok.Headers
-                public enum Body: Sendable, Equatable, Hashable {
+                @frozen public enum Body: Sendable, Equatable, Hashable {
                     case json(Components.Schemas.Pets)
                 }
                 /// Received HTTP response body
@@ -894,7 +894,7 @@ public enum Operations {
                 }
                 /// Received HTTP response headers
                 public var headers: Operations.listPets.Output.Default.Headers
-                public enum Body: Sendable, Equatable, Hashable {
+                @frozen public enum Body: Sendable, Equatable, Hashable {
                     case json(Components.Schemas._Error)
                 }
                 /// Received HTTP response body
@@ -953,7 +953,7 @@ public enum Operations {
                 public init() {}
             }
             public var cookies: Operations.createPet.Input.Cookies
-            public enum Body: Sendable, Equatable, Hashable {
+            @frozen public enum Body: Sendable, Equatable, Hashable {
                 case json(Components.Schemas.CreatePetRequest)
             }
             public var body: Operations.createPet.Input.Body
@@ -979,7 +979,7 @@ public enum Operations {
                 self.body = body
             }
         }
-        public enum Output: Sendable, Equatable, Hashable {
+        @frozen public enum Output: Sendable, Equatable, Hashable {
             public struct Created: Sendable, Equatable, Hashable {
                 public struct Headers: Sendable, Equatable, Hashable {
                     public var X_Extra_Arguments: Components.Schemas.CodeError?
@@ -993,7 +993,7 @@ public enum Operations {
                 }
                 /// Received HTTP response headers
                 public var headers: Operations.createPet.Output.Created.Headers
-                public enum Body: Sendable, Equatable, Hashable {
+                @frozen public enum Body: Sendable, Equatable, Hashable {
                     case json(Components.Schemas.Pet)
                 }
                 /// Received HTTP response body
@@ -1054,7 +1054,7 @@ public enum Operations {
                 public init() {}
             }
             public var cookies: Operations.probe.Input.Cookies
-            public enum Body: Sendable, Equatable, Hashable {}
+            @frozen public enum Body: Sendable, Equatable, Hashable {}
             public var body: Operations.probe.Input.Body?
             /// Creates a new `Input`.
             ///
@@ -1078,7 +1078,7 @@ public enum Operations {
                 self.body = body
             }
         }
-        public enum Output: Sendable, Equatable, Hashable {
+        @frozen public enum Output: Sendable, Equatable, Hashable {
             public struct NoContent: Sendable, Equatable, Hashable {
                 public struct Headers: Sendable, Equatable, Hashable {
                     /// Creates a new `Headers`.
@@ -1086,7 +1086,7 @@ public enum Operations {
                 }
                 /// Received HTTP response headers
                 public var headers: Operations.probe.Output.NoContent.Headers
-                public enum Body: Sendable, Equatable, Hashable {}
+                @frozen public enum Body: Sendable, Equatable, Hashable {}
                 /// Received HTTP response body
                 public var body: Operations.probe.Output.NoContent.Body?
                 /// Creates a new `NoContent`.
@@ -1168,7 +1168,7 @@ public enum Operations {
                 self.body = body
             }
         }
-        public enum Output: Sendable, Equatable, Hashable {
+        @frozen public enum Output: Sendable, Equatable, Hashable {
             public struct NoContent: Sendable, Equatable, Hashable {
                 public struct Headers: Sendable, Equatable, Hashable {
                     /// Creates a new `Headers`.
@@ -1176,7 +1176,7 @@ public enum Operations {
                 }
                 /// Received HTTP response headers
                 public var headers: Operations.updatePet.Output.NoContent.Headers
-                public enum Body: Sendable, Equatable, Hashable {}
+                @frozen public enum Body: Sendable, Equatable, Hashable {}
                 /// Received HTTP response body
                 public var body: Operations.updatePet.Output.NoContent.Body?
                 /// Creates a new `NoContent`.
@@ -1205,7 +1205,7 @@ public enum Operations {
                 }
                 /// Received HTTP response headers
                 public var headers: Operations.updatePet.Output.BadRequest.Headers
-                public enum Body: Sendable, Equatable, Hashable {
+                @frozen public enum Body: Sendable, Equatable, Hashable {
                     /// - Remark: Generated from `#/paths/pets/{petId}/PATCH/json`.
                     public struct jsonPayload: Codable, Equatable, Hashable, Sendable {
                         /// - Remark: Generated from `#/paths/pets/{petId}/PATCH/json/message`.
@@ -1277,7 +1277,7 @@ public enum Operations {
                 public init() {}
             }
             public var cookies: Operations.uploadAvatarForPet.Input.Cookies
-            public enum Body: Sendable, Equatable, Hashable { case binary(Foundation.Data) }
+            @frozen public enum Body: Sendable, Equatable, Hashable { case binary(Foundation.Data) }
             public var body: Operations.uploadAvatarForPet.Input.Body
             /// Creates a new `Input`.
             ///
@@ -1301,7 +1301,7 @@ public enum Operations {
                 self.body = body
             }
         }
-        public enum Output: Sendable, Equatable, Hashable {
+        @frozen public enum Output: Sendable, Equatable, Hashable {
             public struct Ok: Sendable, Equatable, Hashable {
                 public struct Headers: Sendable, Equatable, Hashable {
                     /// Creates a new `Headers`.
@@ -1309,7 +1309,9 @@ public enum Operations {
                 }
                 /// Received HTTP response headers
                 public var headers: Operations.uploadAvatarForPet.Output.Ok.Headers
-                public enum Body: Sendable, Equatable, Hashable { case binary(Foundation.Data) }
+                @frozen public enum Body: Sendable, Equatable, Hashable {
+                    case binary(Foundation.Data)
+                }
                 /// Received HTTP response body
                 public var body: Operations.uploadAvatarForPet.Output.Ok.Body
                 /// Creates a new `Ok`.
@@ -1338,7 +1340,7 @@ public enum Operations {
                 }
                 /// Received HTTP response headers
                 public var headers: Operations.uploadAvatarForPet.Output.PreconditionFailed.Headers
-                public enum Body: Sendable, Equatable, Hashable { case json(Swift.String) }
+                @frozen public enum Body: Sendable, Equatable, Hashable { case json(Swift.String) }
                 /// Received HTTP response body
                 public var body: Operations.uploadAvatarForPet.Output.PreconditionFailed.Body
                 /// Creates a new `PreconditionFailed`.
@@ -1368,7 +1370,7 @@ public enum Operations {
                 }
                 /// Received HTTP response headers
                 public var headers: Operations.uploadAvatarForPet.Output.InternalServerError.Headers
-                public enum Body: Sendable, Equatable, Hashable { case text(Swift.String) }
+                @frozen public enum Body: Sendable, Equatable, Hashable { case text(Swift.String) }
                 /// Received HTTP response body
                 public var body: Operations.uploadAvatarForPet.Output.InternalServerError.Body
                 /// Creates a new `InternalServerError`.