diff --git a/.gitignore b/.gitignore
index 17a22d93f..bf4392768 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+sinfo-requirements.txt
 *.code-workspace
 .vscode/*
 !.vscode/settings.json.default
diff --git a/scirpy/tl/_repertoire_overlap.py b/scirpy/tl/_repertoire_overlap.py
index 2bc0165ce..257cd6681 100644
--- a/scirpy/tl/_repertoire_overlap.py
+++ b/scirpy/tl/_repertoire_overlap.py
@@ -60,11 +60,11 @@ def repertoire_overlap(
 
     # Remove NA rows
     na_mask = _is_na(adata.obs[groupby]) | _is_na(adata.obs[target_col])
-    df = adata.obs.loc[~na_mask, :]
+    df = adata.obs.loc[~na_mask, :].copy()
 
     # Normalize to fractions
-    df = df.assign(
-        cell_weights=_normalize_counts(adata.obs, fraction)
+    df["cell_weights"] = (
+        _normalize_counts(df, fraction)
         if isinstance(fraction, (bool, str)) or fraction is None
         else fraction
     )