diff --git a/plio/io/io_tes.py b/plio/io/io_tes.py
index 7f726f57bfe712a016680a1fdf193250d874d5a3..d084dd7be0bcd6e7032fcd1e4df868f4d0748505 100644
--- a/plio/io/io_tes.py
+++ b/plio/io/io_tes.py
@@ -326,4 +326,4 @@ class Tes(object):
 
         outlier_idx = keyspace-set(merged["sclk_time"])
         outliers = [Tes(tds.data[tds.data['sclk_time'].isin(outlier_idx)], data_set=tds.dataset) for tds in tes_data]
-        return merged, [tds for tds in outliers if not tds.data.empty]`
+        return merged, [tds for tds in outliers if not tds.data.empty]