diff --git a/data/spot.py b/data/spot.py
index 7d841ad..30773e7 100644
--- a/data/spot.py
+++ b/data/spot.py
@@ -388,9 +388,11 @@ class Spot:
     def append_sig_ref_if_missing(self, new_sig_ref):
         if not self.sig_refs:
             self.sig_refs = []
-        if new_sig_ref.id.trim() == "":
+        new_sig_ref.id = new_sig_ref.id.strip().upper()
+        new_sig_ref.sig = new_sig_ref.sig.strip().upper()
+        if new_sig_ref.id == "":
             return
         for sig_ref in self.sig_refs:
-            if sig_ref.id.trim().upper() == new_sig_ref.id.trim().upper() and sig_ref.sig.trim().upper() == new_sig_ref.sig.trim().upper():
+            if sig_ref.id == new_sig_ref.id and sig_ref.sig == new_sig_ref.sig:
                 return
-        self.sig_refs.append(new_sig_ref.trim())
+        self.sig_refs.append(new_sig_ref)