diff --git a/odxtools/comparaminstance.py b/odxtools/comparaminstance.py
index 3ad41ef5..3d8fef9c 100644
--- a/odxtools/comparaminstance.py
+++ b/odxtools/comparaminstance.py
@@ -138,4 +138,9 @@ def get_subvalue(self, subparam_name: str) -> Optional[str]:
 
     @property
     def short_name(self) -> str:
-        return self.spec.short_name
+        if self.spec:
+            return self.spec.short_name
+
+        # ODXLINK IDs allow dots and hyphens, but short names do not.
+        # (This should not happen anyway in a correct PDX...)
+        return self.spec_ref.ref_id.replace(".", "__").replace("-", "_")