diff --git a/mokapot/confidence.py b/mokapot/confidence.py
index 0f13c10d..3760f35b 100644
--- a/mokapot/confidence.py
+++ b/mokapot/confidence.py
@@ -120,7 +120,7 @@ def to_txt(self, dest_dir=None, file_root=None, sep="\t", decoys=False):
                 if qvals is None:
                     continue
 
-                out_file = file_base + f"decoys.{level}.txt"
+                out_file = file_base + f".decoys.{level}.txt"
                 qvals.to_csv(out_file, sep=sep, index=False)
                 out_files.append(out_file)