diff --git a/hermes_merit/__init__.py b/hermes_merit/__init__.py
index 50c39cf..553cf83 100644
--- a/hermes_merit/__init__.py
+++ b/hermes_merit/__init__.py
@@ -1,5 +1,5 @@
 # Licensed under Apache License v2 - see LICENSE.rst
-import os.path
+from pathlib import Path
 
 from hermes_core import log
 from hermes_merit.io.file_tools import read_file
@@ -19,7 +19,7 @@
 INST_TO_SHORTNAME = {INST_NAME: INST_SHORTNAME}
 INST_TO_TARGETNAME = {INST_NAME: INST_TARGETNAME}
 
-_package_directory = os.path.dirname(os.path.abspath(__file__))
-_data_directory = os.path.abspath(os.path.join(_package_directory, "data"))
+_package_directory = Path(__file__).parent
+_data_directory = _package_directory / "data"
 
 log.info(f"hermes_merit version: {__version__}")
diff --git a/hermes_merit/calibration/calibration.py b/hermes_merit/calibration/calibration.py
index 99d8e8a..e9e1057 100644
--- a/hermes_merit/calibration/calibration.py
+++ b/hermes_merit/calibration/calibration.py
@@ -3,7 +3,6 @@
 """
 
 import random
-import os.path
 from pathlib import Path
 
 import ccsdspy
@@ -31,13 +30,14 @@ def process_file(data_filename: Path) -> list:
 
     Parameters
     ----------
-    data_filename: str
-        Fully specificied filename of an input file
+    data_filename: `pathlib.Path`
+        Fully specificied filename of an input file.
+        The file contents: Traditional binary packets in CCSDS format
 
     Returns
     -------
-    output_filenames: list
-        Fully specificied filenames for the output files.
+    output_filenames: `list[pathlib.Path]`
+        Fully specificied filenames for the output CDF files.
     """
     log.info(f"Processing file {data_filename}.")
     output_files = []
@@ -58,12 +58,12 @@ def calibrate_file(data_filename: Path) -> Path:
 
     Parameters
     ----------
-    data_filename: Path
+    data_filename: `pathlib.Path`
         Fully specificied filename of the input data file.
 
     Returns
     -------
-    output_filename: Path
+    output_filename: `pathlib.Path`
         Fully specificied filename of the output file.
 
     Examples
@@ -136,7 +136,7 @@ def parse_l0_sci_packets(data_filename: Path) -> dict:
 
     Parameters
     ----------
-    data_filename: str
+    data_filename: `pathlib.Path`
         Fully specificied filename
 
     Returns
@@ -153,7 +153,7 @@ def parse_l0_sci_packets(data_filename: Path) -> dict:
     log.info(f"Parsing packets from file:{data_filename}.")
 
     pkt = ccsdspy.FixedLength.from_file(
-        os.path.join(hermes_merit._data_directory, "MERIT_sci_packet_def.csv")
+        Path(hermes_merit._data_directory) / "MERIT_sci_packet_def.csv"
     )
     data = pkt.load(data_filename)
     return data
@@ -167,12 +167,12 @@ def l0_sci_data_to_cdf(data: dict, original_filename: Path) -> Path:
     ----------
     data: dict
         A dictionary of arrays which includes the ccsds header fields
-    original_filename: Path
+    original_filename: `pathlib.Path`
         The Path to the originating file.
 
     Returns
     -------
-    output_filename: Path
+    output_filename: `pathlib.Path`
         Fully specificied filename of cdf file
 
     Examples
@@ -207,13 +207,13 @@ def get_calibration_file(data_filename: Path, time=None) -> Path:
 
     Parameters
     ----------
-    data_filename: str
+    data_filename: `pathlib.Path`
         Fully specificied filename of the non-calibrated file (data level < 2)
     time: ~astropy.time.Time
 
     Returns
     -------
-    calib_filename: str
+    calib_filename: `pathlib.Path`
         Fully specificied filename for the appropriate calibration file.
 
     Examples
@@ -228,12 +228,12 @@ def read_calibration_file(calib_filename: Path):
 
     Parameters
     ----------
-    calib_filename: str
+    calib_filename: `pathlib.Path`
         Fully specificied filename of the non-calibrated file (data level < 2)
 
     Returns
     -------
-    output_filename: str
+    output_filename: `pathlib.Path`
         Fully specificied filename of the appropriate calibration file.
 
     Examples
diff --git a/hermes_merit/io/file_tools.py b/hermes_merit/io/file_tools.py
index 3f2f943..525235d 100644
--- a/hermes_merit/io/file_tools.py
+++ b/hermes_merit/io/file_tools.py
@@ -2,16 +2,18 @@
 This module provides a generic file reader.
 """
 
+from pathlib import Path
+
 __all__ = ["read_file"]
 
 
-def read_file(data_filename):
+def read_file(data_filename: Path):
     """
     Read a file.
 
     Parameters
     ----------
-    data_filename: str
+    data_filename: `pathlib.Path`
         A file to read.
 
     Returns
diff --git a/hermes_merit/tests/test_calibration.py b/hermes_merit/tests/test_calibration.py
index d7660fc..554b1f9 100644
--- a/hermes_merit/tests/test_calibration.py
+++ b/hermes_merit/tests/test_calibration.py
@@ -1,5 +1,4 @@
 import pytest
-import os.path
 from pathlib import Path
 
 import hermes_merit.calibration as calib
diff --git a/hermes_merit/tests/test_file_tools.py b/hermes_merit/tests/test_file_tools.py
index 3b146e4..cc01859 100644
--- a/hermes_merit/tests/test_file_tools.py
+++ b/hermes_merit/tests/test_file_tools.py
@@ -1,5 +1,6 @@
+from pathlib import Path
 from hermes_merit.io.file_tools import read_file
 
 
 def test_read_file():
-    assert read_file("test_file.cdf") is None
+    assert read_file(Path("test_file.cdf")) is None