diff --git a/src/fusor/models.py b/src/fusor/models.py
index faea494..4db1f59 100644
--- a/src/fusor/models.py
+++ b/src/fusor/models.py
@@ -513,7 +513,7 @@ def structure_ends(cls, values):
         """
         elements = values.structure
         if isinstance(elements[0], TranscriptSegmentElement):
-            if elements[0].exonEnd is None and not values["regulatoryElement"]:
+            if elements[0].exonEnd is None and not values.regulatoryElement:
                 msg = "5' TranscriptSegmentElement fusion partner must contain ending exon position"
                 raise ValueError(msg)
         elif isinstance(elements[0], LinkerElement):