diff --git a/src/hla_algorithm/hla_algorithm.py b/src/hla_algorithm/hla_algorithm.py
index 07240f8..9e81e02 100644
--- a/src/hla_algorithm/hla_algorithm.py
+++ b/src/hla_algorithm/hla_algorithm.py
@@ -80,8 +80,8 @@ def __init__(
     @classmethod
     def use_config(
         cls,
-        standards_path: Optional[str] = None,
-        frequencies_path: Optional[str] = None,
+        standards_path: str | Path | None = None,
+        frequencies_path: str | Path | None = None,
     ) -> "HLAAlgorithm":
         """
         An alternate constructor that accepts file paths for the configuration.
@@ -90,11 +90,11 @@ def use_config(
         frequencies: Optional[dict[HLA_LOCUS, dict[HLAProteinPair, int]]] = None
 
         if standards_path is not None:
-            with open(standards_path) as f:
+            with Path(standards_path).open() as f:
                 processed_stds = cls.read_hla_standards(f)
 
         if frequencies_path is not None:
-            with open(frequencies_path) as f:
+            with Path(frequencies_path).open() as f:
                 frequencies = cls.read_hla_frequencies(f)
 
         return cls(processed_stds, frequencies)
@@ -138,9 +138,9 @@ def load_default_hla_standards() -> LoadedStandards:
         :return: List of known HLA standards
         :rtype: list[HLAStandard]
         """
-        with open(
+        with (
             HLAAlgorithm.DEFAULT_CONFIG_DIR / "hla_standards.yaml"
-        ) as standards_file:
+        ).open() as standards_file:
             return HLAAlgorithm.read_hla_standards(standards_file)
 
     FREQUENCY_LOCUS_COLUMNS: dict[HLA_LOCUS, tuple[str, str]] = {
@@ -202,7 +202,7 @@ def load_default_hla_frequencies() -> dict[HLA_LOCUS, dict[HLAProteinPair, int]]
         :rtype: dict[HLA_LOCUS, dict[HLAProteinPair, int]]
         """
         hla_freqs: dict[HLA_LOCUS, dict[HLAProteinPair, int]]
-        with open(HLAAlgorithm.DEFAULT_CONFIG_DIR / "hla_frequencies.csv") as f:
+        with (HLAAlgorithm.DEFAULT_CONFIG_DIR / "hla_frequencies.csv").open() as f:
             hla_freqs = HLAAlgorithm.read_hla_frequencies(f)
         return hla_freqs
 
diff --git a/src/hla_algorithm/interpret_from_json.py b/src/hla_algorithm/interpret_from_json.py
index 554c68f..bc91616 100644
--- a/src/hla_algorithm/interpret_from_json.py
+++ b/src/hla_algorithm/interpret_from_json.py
@@ -3,6 +3,8 @@
 import argparse
 import json
 import logging
+import sys
+from pathlib import Path
 
 from .hla_algorithm import HLAAlgorithm
 from .interpret_from_json_lib import HLAInput, HLAResult
@@ -17,14 +19,18 @@ def main():
     )
     parser.add_argument(
         "infile",
-        type=argparse.FileType("r"),
+        type=str,
         help='Input file containing the JSON input (use "-" to read from stdin)',
     )
     args: argparse.Namespace = parser.parse_args()
 
     hla_input_str: str = ""
-    with args.infile:
-        for line in args.infile:
+    if args.infile == "-":
+        input_file = sys.stdin
+    else:
+        input_file = Path(args.infile).open()
+    with input_file:
+        for line in input_file:
             hla_input_str += f"{line}\n"
 
     hla_input: HLAInput = HLAInput(**json.loads(hla_input_str))
diff --git a/src/hla_algorithm/interpret_from_json_lib.py b/src/hla_algorithm/interpret_from_json_lib.py
index f58d046..1be5341 100644
--- a/src/hla_algorithm/interpret_from_json_lib.py
+++ b/src/hla_algorithm/interpret_from_json_lib.py
@@ -1,5 +1,5 @@
 from datetime import datetime
-from typing import Optional
+from pathlib import Path
 
 from pydantic import BaseModel, Field
 
@@ -24,11 +24,11 @@
 
 class HLAInput(BaseModel):
     seq1: str
-    seq2: Optional[str]
+    seq2: str | None
     locus: HLA_LOCUS
-    threshold: Optional[int] = None
-    hla_std_path: Optional[str] = None
-    hla_freq_path: Optional[str] = None
+    threshold: int | None = None
+    hla_std_path: Path | None = None
+    hla_freq_path: Path | None = None
 
     def check_sequences(self) -> list[str]:
         errors: list[str] = []
@@ -113,7 +113,7 @@ class HLAResult(BaseModel):
     alleles_version: str = ""
     alleles_last_updated: datetime = Field(default_factory=datetime.now)
     b5701: bool = False
-    dist_b5701: Optional[int] = None
+    dist_b5701: int | None = None
     errors: list[str] = Field(default_factory=list)
     all_mismatches: dict[str, HLAMatchAdaptor] = Field(default_factory=dict)
 
@@ -144,7 +144,9 @@ def build_from_interpretation(
 
         return HLAResult(
             seqs=seqs,
-            alleles_all=[f"{x[0]} - {x[1]}" for x in sort_allele_pairs(aps.allele_pairs)],
+            alleles_all=[
+                f"{x[0]} - {x[1]}" for x in sort_allele_pairs(aps.allele_pairs)
+            ],
             alleles_clean=alleles_clean,
             alleles_for_mismatches=f"{rep_ap[0]} - {rep_ap[1]}",
             mismatches=[str(x) for x in match_details.mismatches],
diff --git a/src/hla_algorithm/reformat_old_alleles.py b/src/hla_algorithm/reformat_old_alleles.py
index 84d25e3..5557f13 100644
--- a/src/hla_algorithm/reformat_old_alleles.py
+++ b/src/hla_algorithm/reformat_old_alleles.py
@@ -4,13 +4,14 @@
 import csv
 import logging
 from datetime import datetime
+from pathlib import Path
 from typing import cast
 
 import yaml
 
 from .utils import (
-    GroupedAllele,
     HLA_LOCUS,
+    GroupedAllele,
     HLARawStandard,
     StoredHLAStandards,
     group_identical_alleles,
@@ -28,22 +29,22 @@ def main():
     parser.add_argument(
         "a_standards",
         help="CSV file containing all HLA-A alleles",
-        type=str,
+        type=Path,
     )
     parser.add_argument(
         "b_standards",
         help="CSV file containing all HLA-B alleles",
-        type=str,
+        type=Path,
     )
     parser.add_argument(
         "c_standards",
         help="CSV file containing all HLA-C alleles",
-        type=str,
+        type=Path,
     )
     parser.add_argument(
         "--output",
         help="filename to store the reformatted standards in YAML",
-        type=str,
+        type=Path,
         default="reformatted_hla_standards.yaml",
     )
     parser.add_argument(
@@ -84,7 +85,7 @@ def main():
     grouped_alleles: dict[HLA_LOCUS, list[GroupedAllele]] = {"A": [], "B": [], "C": []}
     for locus in ("A", "B", "C"):
         logger.info(f"Grouping HLA-{locus} alleles....")
-        with open(input_filenames_by_locus[locus]) as f:
+        with input_filenames_by_locus[locus].open() as f:
             standards_csv: csv.DictReader = csv.DictReader(
                 f,
                 fieldnames=("allele", "exon2", "exon3"),
@@ -114,7 +115,7 @@ def main():
     )
 
     logger.info(f"Writing HLA standards to {args.output}....")
-    with open(args.output, "w") as f:
+    with args.output.open("w") as f:
         yaml.safe_dump(standards_for_saving.model_dump(), f)
 
     logger.info("Done.")
diff --git a/src/hla_algorithm/update_alleles.py b/src/hla_algorithm/update_alleles.py
index d62e18d..bfd20b1 100644
--- a/src/hla_algorithm/update_alleles.py
+++ b/src/hla_algorithm/update_alleles.py
@@ -8,6 +8,7 @@
 import time
 from datetime import datetime
 from io import StringIO
+from pathlib import Path
 from typing import Final, Optional, TypedDict, cast
 
 import Bio
@@ -215,13 +216,13 @@ def main():
     parser.add_argument(
         "--output",
         help="filename to store the unreduced standards (YAML format)",
-        type=str,
+        type=Path,
         default="hla_standards.yaml",
     )
     parser.add_argument(
         "--checksum",
         help="filename to store the MD5 checksum of the retrieved data in",
-        type=str,
+        type=Path,
         default="hla_nuc.fasta.checksum.txt",
     )
     parser.add_argument(
@@ -242,8 +243,7 @@ def main():
     parser.add_argument(
         "--dump_full_fasta_to",
         help="if specified, the full original FASTA file is dumped to the specified path",
-        type=str,
-        default="",
+        type=Path,
     )
     parser.add_argument(
         "--standard_report_interval",
@@ -278,16 +278,14 @@ def main():
         f"{retrieval_datetime}."
     )
 
-    if args.dump_full_fasta_to != "":
+    if args.dump_full_fasta_to is not None:
         logger.info(f"Dumping the full FASTA file to {args.dump_full_fasta_to}.")
-        with open(args.dump_full_fasta_to, "w") as f:
-            f.write(alleles_str)
+        args.dump_full_fasta_to.write_text(alleles_str)
 
     # Compute the checksum.
     md5_calc = hashlib.md5()
     md5_calc.update(alleles_str.encode())
-    with open(args.checksum, "w") as f:
-        f.write(f"{md5_calc.hexdigest()} {HLA_ALLELES_FILENAME}\n")
+    args.checksum.write_text(f"{md5_calc.hexdigest()} {HLA_ALLELES_FILENAME}\n")
 
     raw_standards: dict[HLA_LOCUS, list[HLARawStandard]] = collate_standards(
         list(Bio.SeqIO.parse(StringIO(alleles_str), "fasta")),
@@ -313,7 +311,7 @@ def main():
 
     # First, prepare the unreduced YAML output.
     logger.info(f"Writing HLA standards to {args.output}....")
-    with open(args.output, "w") as f:
+    with args.output.open("w") as f:
         yaml.safe_dump(standards_for_saving.model_dump(), f)
 
     logger.info("Done.")
diff --git a/src/scripts/measure_resources.py b/src/scripts/measure_resources.py
index 904502a..3d0066d 100644
--- a/src/scripts/measure_resources.py
+++ b/src/scripts/measure_resources.py
@@ -90,7 +90,7 @@ def main():
             }
         )
 
-    with open(args.output_csv, "w") as f:
+    with args.output_csv.open("w") as f:
         resource_summary_writer = csv.DictWriter(
             f,
             fieldnames=("sample_name", "wall_clock_time", "max_memory_usage_kb"),