diff --git a/nireports/assembler/report.py b/nireports/assembler/report.py
index 3a6f0549..9e7b5ccf 100644
--- a/nireports/assembler/report.py
+++ b/nireports/assembler/report.py
@@ -255,13 +255,13 @@ def __init__(
         if bids_filters.get("subject"):
             subject_id = bids_filters["subject"]
             bids_filters["subject"] = (
-                subject_id[4:] if subject_id.startswith("sub-") else subject_id
+                subject_id.removeprefix("sub-")
             )
 
         if bids_filters.get("session"):
             session_id = bids_filters["session"]
             bids_filters["session"] = (
-                session_id[4:] if session_id.startswith("ses-") else session_id
+                session_id.removeprefix("ses-")
             )
 
         if bids_filters and out_filename == "report.html":