diff --git a/api/s23_options_v3.py b/api/s23_options_v3.py
index cabf6cf..4e62c88 100644
--- a/api/s23_options_v3.py
+++ b/api/s23_options_v3.py
@@ -16,7 +16,8 @@ def _parse_v2(v2_lines: list[str]) -> dict[str, str]:
     for s in v2_lines:
         tokens = s.split()
         if tokens[0].upper() == 'PATTERN': # can not upper id
-            cs_v2 |= { 'PATTERN' : tokens[1] }
+            value = tokens[1] if len(tokens) > 1 else ''
+            cs_v2 |= { 'PATTERN' : value }
         elif tokens[0].upper() == 'QUALITY': # can not upper trace node
             value = tokens[1]
             if len(tokens) > 2: