diff --git a/homeassistant/components/dsmr_reader/definitions.py b/homeassistant/components/dsmr_reader/definitions.py
index e020be02e21..9003c4d4334 100644
--- a/homeassistant/components/dsmr_reader/definitions.py
+++ b/homeassistant/components/dsmr_reader/definitions.py
@@ -25,14 +25,14 @@ PRICE_EUR_KWH: Final = f"EUR/{UnitOfEnergy.KILO_WATT_HOUR}"
 PRICE_EUR_M3: Final = f"EUR/{UnitOfVolume.CUBIC_METERS}"
 
 
-def dsmr_transform(value):
+def dsmr_transform(value: str) -> float | str:
     """Transform DSMR version value to right format."""
     if value.isdigit():
         return float(value) / 10
     return value
 
 
-def tariff_transform(value):
+def tariff_transform(value: str) -> str:
     """Transform tariff from number to description."""
     if value == "1":
         return "low"