diff --git a/src/driftpy/drift_user.py b/src/driftpy/drift_user.py
index 59673da1..d23cc826 100644
--- a/src/driftpy/drift_user.py
+++ b/src/driftpy/drift_user.py
@@ -142,6 +142,9 @@ def get_perp_market_liability(
         signed: bool = False,
     ):
         perp_position = self.get_perp_position(market_index)
+        if perp_position is None:
+            return 0
+
         return self.calculate_weighted_perp_position_liability(
             perp_position,
             margin_category,