diff --git a/backend/models.py b/backend/models.py
index b89e884..6fcc647 100644
--- a/backend/models.py
+++ b/backend/models.py
@@ -5,7 +5,7 @@ from pydantic import BaseModel, Field
 
 
 class RegisterRequest(BaseModel):
-    uuid: str = Field(..., min_length=1)
+    uuid: str = Field(..., pattern=r'^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$')
     name: str = Field(..., min_length=1, max_length=100)
 
 
@@ -21,7 +21,7 @@ class GeoData(BaseModel):
 
 
 class SignalRequest(BaseModel):
-    user_id: str = Field(..., min_length=1)
+    user_id: str = Field(..., pattern=r'^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$')
     timestamp: int = Field(..., gt=0)
     geo: Optional[GeoData] = None