diff --git a/src/preprocess.py b/src/preprocess.py
index f09e25e..1d4e9d9 100644
--- a/src/preprocess.py
+++ b/src/preprocess.py
@@ -129,7 +129,7 @@ def mqttOnMessageCallback(client, userdata, message):
             "application": variable["application"],
             "variable": variable["variable"],
             "unit": variable["unit"],
-            "value": payload
+            "value": float(payload)
         }
         
         logger.debug(f"{measurement=}")