diff --git a/server/backend/adapters/http/readings.py b/server/backend/adapters/http/readings.py
index 3807998..9fb12ca 100644
--- a/server/backend/adapters/http/readings.py
+++ b/server/backend/adapters/http/readings.py
@@ -1,7 +1,8 @@
 from datetime import datetime
 from typing import Annotated
 
-from fastapi import APIRouter, Depends, Query, HTTPException
+from fastapi import APIRouter, Depends, Query, HTTPException, Path
+from pydantic import constr
 
 from domain.value_objects import Granularity
 from domain.exceptions import ValidationError, DatabaseError
@@ -12,10 +13,11 @@ from ._readings_schemas import ConsumptionResponseSchema
 
 readings_router = APIRouter(prefix="/readings", tags=["readings"])
 
+DevEUI = Annotated[constr(max_length=64, pattern=r'^[0-9A-Fa-f]+$'), Path()]
 
 @readings_router.get("/{dev_eui}", response_model=ConsumptionResponseSchema)
 def get_consumption(
-    dev_eui: str,
+    dev_eui: DevEUI,
     start: Annotated[datetime, Query()],
     end: Annotated[datetime, Query()],
     granularity: Annotated[Granularity, Query()] = "day",