diff --git a/manifest_assets/base_info.json b/manifest_assets/base_info.json
index 5ff2fe36b..717ed0740 100644
--- a/manifest_assets/base_info.json
+++ b/manifest_assets/base_info.json
@@ -1,9 +1,5 @@
 {
     "manifest_version": "0.12.0",
     "name": "dummy name",
-    "icon": "",
-    "default_sampling_rate": 24000,
-    "terms_of_service": "",
-    "update_infos": [],
-    "dependency_licenses": []
+    "default_sampling_rate": 24000
 }
\ No newline at end of file
diff --git a/voicevox_engine/engine_manifest/EngineManifest.py b/voicevox_engine/engine_manifest/EngineManifest.py
index 90dd848bb..5d78a5d82 100644
--- a/voicevox_engine/engine_manifest/EngineManifest.py
+++ b/voicevox_engine/engine_manifest/EngineManifest.py
@@ -36,6 +36,3 @@ class EngineManifest(BaseModel):
     terms_of_service: str = Field(title="エンジンの利用規約")
     update_infos: List[UpdateInfo] = Field(title="エンジンのアップデート情報")
     dependency_licenses: List[LicenseInfo] = Field(title="依存関係のライセンス情報")
-
-    class Config:
-        validate_assignment = True
diff --git a/voicevox_engine/engine_manifest/EngineManifestLoader.py b/voicevox_engine/engine_manifest/EngineManifestLoader.py
index 82e94c422..60e40e1d8 100644
--- a/voicevox_engine/engine_manifest/EngineManifestLoader.py
+++ b/voicevox_engine/engine_manifest/EngineManifestLoader.py
@@ -11,24 +11,24 @@ def __init__(self, assets_dir: Path):
 
     def load_manifest(self) -> EngineManifest:
         manifest = EngineManifest(
-            **json.load((self.assets_dir / "base_info.json").open(encoding="utf-8"))
+            **json.load((self.assets_dir / "base_info.json").open(encoding="utf-8")),
+            icon=b64encode((self.assets_dir / "icon.png").read_bytes()).decode("utf-8"),
+            terms_of_service=(self.assets_dir / "terms_of_service.md").read_text(
+                encoding="utf-8"
+            ),
+            update_infos=[
+                UpdateInfo(**update_info)
+                for update_info in json.load(
+                    (self.assets_dir / "update_infos.json").open(encoding="utf-8")
+                )
+            ],
+            dependency_licenses=[
+                LicenseInfo(**license_info)
+                for license_info in json.load(
+                    (self.assets_dir / "dependency_licenses.json").open(
+                        encoding="utf-8"
+                    )
+                )
+            ],
         )
-        manifest.icon = b64encode((self.assets_dir / "icon.png").read_bytes()).decode(
-            "utf-8"
-        )
-        manifest.terms_of_service = (self.assets_dir / "terms_of_service.md").read_text(
-            encoding="utf-8"
-        )
-        manifest.update_infos = [
-            UpdateInfo(**update_info)
-            for update_info in json.load(
-                (self.assets_dir / "update_infos.json").open(encoding="utf-8")
-            )
-        ]
-        manifest.dependency_licenses = [
-            LicenseInfo(**license_info)
-            for license_info in json.load(
-                (self.assets_dir / "dependency_licenses.json").open(encoding="utf-8")
-            )
-        ]
         return manifest