diff --git a/antarest/study/web/raw_studies_blueprint.py b/antarest/study/web/raw_studies_blueprint.py
index a62a08b207..1105a5f74a 100644
--- a/antarest/study/web/raw_studies_blueprint.py
+++ b/antarest/study/web/raw_studies_blueprint.py
@@ -136,7 +136,18 @@ def get_study(
                 # because it's better to avoid raising an exception.
                 return Response(content=output, media_type="application/octet-stream")
 
-        return JSONResponse(content=output)
+        # We want to allow `NaN`, `+Infinity`, and `-Infinity` values in the JSON response
+        # even though they are not standard JSON values because they are supported in JavaScript.
+        # Additionally, we cannot use `orjson` because, despite its superior performance, it converts
+        # `NaN` and other values to `null`, even when using a custom encoder.
+        json_response = json.dumps(
+            output,
+            ensure_ascii=False,
+            allow_nan=True,
+            indent=None,
+            separators=(",", ":"),
+        ).encode("utf-8")
+        return Response(content=json_response, media_type="application/json")
 
     @bp.post(
         "/studies/{uuid}/raw",
diff --git a/tests/integration/raw_studies_blueprint/test_fetch_raw_data.py b/tests/integration/raw_studies_blueprint/test_fetch_raw_data.py
index 96366c6e44..7b5bc4e38e 100644
--- a/tests/integration/raw_studies_blueprint/test_fetch_raw_data.py
+++ b/tests/integration/raw_studies_blueprint/test_fetch_raw_data.py
@@ -4,6 +4,7 @@
 import shutil
 from urllib.parse import urlencode
 
+import numpy as np
 import pytest
 from starlette.testclient import TestClient
 
@@ -41,6 +42,7 @@ def test_get_study(
         with db():
             study: RawStudy = db.session.get(Study, study_id)
             study_dir = pathlib.Path(study.path)
+        headers = {"Authorization": f"Bearer {user_access_token}"}
 
         shutil.copytree(
             ASSETS_DIR.joinpath("user"),
@@ -55,7 +57,7 @@ def test_get_study(
             query_string = urlencode({"path": f"/{rel_path}", "depth": 1})
             res = client.get(
                 f"/v1/studies/{study_id}/raw?{query_string}",
-                headers={"Authorization": f"Bearer {user_access_token}"},
+                headers=headers,
             )
             res.raise_for_status()
             if file_path.suffix == ".json":
@@ -81,7 +83,7 @@ def test_get_study(
             query_string = urlencode({"path": f"/{rel_path.as_posix()}", "depth": 1})
             res = client.get(
                 f"/v1/studies/{study_id}/raw?{query_string}",
-                headers={"Authorization": f"Bearer {user_access_token}"},
+                headers=headers,
             )
             res.raise_for_status()
             actual = res.content
@@ -95,7 +97,7 @@ def test_get_study(
             query_string = urlencode({"path": f"/{rel_path.as_posix()}", "depth": 1})
             res = client.get(
                 f"/v1/studies/{study_id}/raw?{query_string}",
-                headers={"Authorization": f"Bearer {user_access_token}"},
+                headers=headers,
             )
             assert res.status_code == http.HTTPStatus.UNPROCESSABLE_ENTITY
 
@@ -104,7 +106,15 @@ def test_get_study(
         query_string = urlencode({"path": "/input/areas/list", "depth": 1})
         res = client.get(
             f"/v1/studies/{study_id}/raw?{query_string}",
-            headers={"Authorization": f"Bearer {user_access_token}"},
+            headers=headers,
         )
         res.raise_for_status()
         assert res.json() == ["DE", "ES", "FR", "IT"]
+
+        # asserts that the GET /raw endpoint is able to read matrix containing NaN values
+        res = client.get(
+            f"/v1/studies/{study_id}/raw?path=output/20201014-1427eco/economy/mc-all/areas/de/id-monthly",
+            headers=headers,
+        )
+        assert res.status_code == 200
+        assert np.isnan(res.json()["data"][0]).any()
diff --git a/tests/integration/test_integration_xpansion.py b/tests/integration/test_integration_xpansion.py
index f4f4648605..0aa0579734 100644
--- a/tests/integration/test_integration_xpansion.py
+++ b/tests/integration/test_integration_xpansion.py
@@ -1,18 +1,14 @@
 import io
 from pathlib import Path
 
-from fastapi import FastAPI
 from starlette.testclient import TestClient
 
 from antarest.study.business.area_management import AreaType
 from antarest.study.business.xpansion_management import XpansionCandidateDTO
 
 
-def test_integration_xpansion(app: FastAPI, tmp_path: Path):
-    client = TestClient(app, raise_server_exceptions=False)
-    res = client.post("/v1/login", json={"username": "admin", "password": "admin"})
-    admin_credentials = res.json()
-    headers = {"Authorization": f'Bearer {admin_credentials["access_token"]}'}
+def test_integration_xpansion(client: TestClient, tmp_path: Path, admin_access_token: str):
+    headers = {"Authorization": f"Bearer {admin_access_token}"}
 
     created = client.post(
         "/v1/studies?name=foo",