diff --git a/backend/pyproject.toml b/backend/pyproject.toml
index cd295ff0..5f67ae3d 100644
--- a/backend/pyproject.toml
+++ b/backend/pyproject.toml
@@ -16,7 +16,7 @@ dependencies = [
     "python-multipart>=0.0.32",
     "loguru>=0.7.3",
     "tzdata>=2026.2",
-    "simplejson (>=3.17.6,<4.0.0)",
+    "simplejson (>=3.17.6,<5.0.0)",
     "pydantic-settings (>=2.7.1,<3.0.0)",
     "pydantic-extra-types (>=2.10.2,<3.0.0)",
     "psycopg[binary]>=3.3.4",