diff --git a/adafruit_fona/adafruit_fona_socket.py b/adafruit_fona/adafruit_fona_socket.py
index 7aa210b..c20c518 100644
--- a/adafruit_fona/adafruit_fona_socket.py
+++ b/adafruit_fona/adafruit_fona_socket.py
@@ -231,7 +231,7 @@ def settimeout(self, value: int) -> None:
         :param int value: Socket read timeout, in seconds.
         """
         if value < 0:
-            raise Exception("Timeout period should be non-negative.")
+            raise ValueError("Timeout period should be non-negative.")
         self._timeout = value
 
     def gettimeout(self) -> int: