diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index f052d43..3171329 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -9,7 +9,7 @@ repos:
       - id: check-case-conflict
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.14.1
+    rev: v0.14.7
     hooks:
       - id: ruff
         types_or: [python, pyi, jupyter]
diff --git a/bioframe/core/checks.py b/bioframe/core/checks.py
index ba00ddd..88a413b 100644
--- a/bioframe/core/checks.py
+++ b/bioframe/core/checks.py
@@ -169,7 +169,7 @@ def is_overlapping(df, cols=None):
     """
     from ..ops import merge
 
-    ck1, sk1, ek1 = _get_default_colnames() if cols is None else cols
+    _ck1, sk1, ek1 = _get_default_colnames() if cols is None else cols
 
     df_merged = merge(df, cols=cols)
 
@@ -297,8 +297,8 @@ def is_contained(
     """
     from ..ops import trim
 
-    ck1, sk1, ek1 = _get_default_colnames() if cols is None else cols
-    ck2, sk2, ek2 = _get_default_colnames() if cols_view is None else cols_view
+    _ck1, sk1, ek1 = _get_default_colnames() if cols is None else cols
+    _ck2, sk2, ek2 = _get_default_colnames() if cols_view is None else cols_view
     if df_view_col is None:
         try:
             df_view_assigned = ops.overlap(df, view_df, cols1=cols, cols2=cols_view)
diff --git a/bioframe/core/construction.py b/bioframe/core/construction.py
index b7363a5..481adf5 100644
--- a/bioframe/core/construction.py
+++ b/bioframe/core/construction.py
@@ -229,7 +229,7 @@ def make_viewframe(
     view_df:dataframe satisfying properties of a view
 
     """
-    ck1, sk1, ek1 = _get_default_colnames() if cols is None else cols
+    ck1, _sk1, _ek1 = _get_default_colnames() if cols is None else cols
 
     view_df = from_any(regions, name_col=view_name_col, cols=cols)
 
diff --git a/bioframe/ops.py b/bioframe/ops.py
index dfc42d4..8318075 100644
--- a/bioframe/ops.py
+++ b/bioframe/ops.py
@@ -880,8 +880,8 @@ def coverage(
 
     """
 
-    ck1, sk1, ek1 = _get_default_colnames() if cols1 is None else cols1
-    ck2, sk2, ek2 = _get_default_colnames() if cols2 is None else cols2
+    _ck1, sk1, ek1 = _get_default_colnames() if cols1 is None else cols1
+    _ck2, _sk2, _ek2 = _get_default_colnames() if cols2 is None else cols2
 
     df1.reset_index(inplace=True, drop=True)
 
@@ -1365,8 +1365,8 @@ def setdiff(df1, df2, cols1=None, cols2=None, on=None):
     df_setdiff : pandas.DataFrame
 
     """
-    ck1, sk1, ek1 = _get_default_colnames() if cols1 is None else cols1
-    ck2, sk2, ek2 = _get_default_colnames() if cols2 is None else cols2
+    _ck1, _sk1, _ek1 = _get_default_colnames() if cols1 is None else cols1
+    _ck2, _sk2, _ek2 = _get_default_colnames() if cols2 is None else cols2
 
     events1, _ = _overlap_intidxs(
         df1, df2, how="inner", cols1=cols1, cols2=cols2, on=on
@@ -1866,7 +1866,7 @@ def assign_view(
 
     """
 
-    ck1, sk1, ek1 = _get_default_colnames() if cols is None else cols
+    _ck1, sk1, ek1 = _get_default_colnames() if cols is None else cols
 
     df = df.copy()
     df.reset_index(inplace=True, drop=True)