diff --git a/syncall/tw_caldav_utils.py b/syncall/tw_caldav_utils.py
index bd9da4b..b277d42 100644
--- a/syncall/tw_caldav_utils.py
+++ b/syncall/tw_caldav_utils.py
@@ -88,8 +88,12 @@ def convert_tw_to_caldav(tw_item: Item) -> Item:
         tw_item=tw_item,
     )
 
-    # Priority
-    if "priority" in tw_item:
+    # Priority - tw treats priority as a UDA, so any custom options just ignore for now
+    if (
+        "priority" in tw_item.keys()
+        and tw_item["priority"].lower() in aliases_tw_caldav_priority.keys()
+    ):
+
         caldav_item["priority"] = aliases_tw_caldav_priority[tw_item["priority"].lower()]
     else:
         caldav_item["priority"] = ""
diff --git a/tests/test_tw_caldav_conversions.py b/tests/test_tw_caldav_conversions.py
index c84e5ec..0e32c9f 100644
--- a/tests/test_tw_caldav_conversions.py
+++ b/tests/test_tw_caldav_conversions.py
@@ -156,7 +156,7 @@ def caldav_item_with_priority(prio: int) -> dict:
                 tw_pending_item_with_priority(tw_prio),
                 caldav_item_with_priority(caldav_prio),
             )
-            for tw_prio, caldav_prio in [("L", 9), ("M", 5), ("H", 1)]
+            for tw_prio, caldav_prio in [("L", 9), ("M", 5), ("H", 1), ("T", 0)]
         ),
     ],
     ids=[
@@ -169,6 +169,7 @@ def caldav_item_with_priority(prio: int) -> dict:
         "pending_item_with_priority_L",
         "pending_item_with_priority_M",
         "pending_item_with_priority_H",
+        "pending_item_with_priority_T",
     ],
 )
 def test_convert_tw_to_caldav_n_back(tw_item, caldav_item_expected):