diff --git a/src/parse/tnt.py b/src/parse/tnt.py
index 0cf351e..1b0e1ec 100644
--- a/src/parse/tnt.py
+++ b/src/parse/tnt.py
@@ -34,7 +34,7 @@ def parseTnT(file_manager, dataset_id, deconv_mzML, anno_mzML, tag_tsv, protein_
         }
     )
     protein_df['description'] = protein_df['description'].apply(
-        lambda x: x[:50] + '...' if len(x) > 50 else x
+        lambda x: str(x)[:50] + '...' if len(str(x)) > 50 else str(x)
     )
     file_manager.store_data(dataset_id, 'protein_dfs', protein_df)
     logger.log("30.0 %", level=2)