diff --git a/peppy/project.py b/peppy/project.py
index 9f46cccc..85ac3c47 100644
--- a/peppy/project.py
+++ b/peppy/project.py
@@ -807,7 +807,7 @@ def attr_merge(self):
                 if len(this_sample_rows) == 0:
                     _LOGGER.debug(
                         "No merge rows for sample '%s', skipping",
-                        sample[SAMPLE_NAME_ATTR],
+                        sample[self.st_index],
                     )
                     continue
                 _LOGGER.debug("%d rows to merge", len(this_sample_rows))