diff --git a/mvt/ios/modules/mixed/sms.py b/mvt/ios/modules/mixed/sms.py
index 5f711da..e5743cf 100644
--- a/mvt/ios/modules/mixed/sms.py
+++ b/mvt/ios/modules/mixed/sms.py
@@ -53,7 +53,7 @@ class SMS(IOSExtraction):
             },
         ]
         # If the message was read, we add an extra event.
-        if record["isodate_read"]:
+        if record.get("isodate_read", None):
             records.append(
                 {
                     "timestamp": record["isodate_read"],