diff --git a/src/openai/_utils/_utils.py b/src/openai/_utils/_utils.py
index d2bfc91a70..83f88cc3e7 100644
--- a/src/openai/_utils/_utils.py
+++ b/src/openai/_utils/_utils.py
@@ -230,7 +230,7 @@ def human_join(seq: Sequence[str], *, delim: str = ", ", final: str = "or") -> s
 
 def quote(string: str) -> str:
     """Add single quotation marks around the given string. Does *not* do any escaping."""
-    return "'" + string + "'"
+    return f"'{string}'"
 
 
 def required_args(*variants: Sequence[str]) -> Callable[[CallableT], CallableT]:
diff --git a/src/openai/lib/_validators.py b/src/openai/lib/_validators.py
index c8608c0cef..ae48aafa88 100644
--- a/src/openai/lib/_validators.py
+++ b/src/openai/lib/_validators.py
@@ -309,10 +309,10 @@ def common_completion_prefix_validator(df: pd.DataFrame) -> Remediation:
         return Remediation(name="common_prefix")
 
     def remove_common_prefix(x: Any, prefix: Any, ws_prefix: Any) -> Any:
-        x["completion"] = x["completion"].str[len(prefix) :]
+        x["completion"] = x["completion"].str[len(prefix):]
         if ws_prefix:
             # keep the single whitespace as prefix
-            x["completion"] = " " + x["completion"]
+            x["completion"] = f" {x['completion']}"
         return x
 
     if (df.completion == common_prefix).all():
@@ -624,7 +624,7 @@ def get_outfnames(fname: str, split: bool) -> list[str]:
     while True:
         index_suffix = f" ({i})" if i > 0 else ""
         candidate_fnames = [
-            os.path.splitext(fname)[0] + "_prepared" + suffix + index_suffix + ".jsonl" for suffix in suffixes
+            f"{os.path.splitext(fname)[0]}_prepared{suffix}{index_suffix}.jsonl" for suffix in suffixes
         ]
         if not any(os.path.isfile(f) for f in candidate_fnames):
             return candidate_fnames
diff --git a/tests/test_required_args.py b/tests/test_required_args.py
index 1de017db24..5d1a5224ff 100644
--- a/tests/test_required_args.py
+++ b/tests/test_required_args.py
@@ -43,7 +43,7 @@ def foo(*, a: str | None = None) -> str | None:
 def test_multiple_params() -> None:
     @required_args(["a", "b", "c"])
     def foo(a: str = "", *, b: str = "", c: str = "") -> str | None:
-        return a + " " + b + " " + c
+        return f"{a} {b} {c}"
 
     assert foo(a="a", b="b", c="c") == "a b c"