diff --git a/README.md b/README.md
index 8dc93e1..d0a8815 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,6 @@
 
 Requirements:
 * python >= 3.10 (written and tested with 3.11)
-* numpy
 
 
 Install with pip:
diff --git a/g85/__init__.py b/g85/__init__.py
index 8df75f7..69c0e4b 100644
--- a/g85/__init__.py
+++ b/g85/__init__.py
@@ -1,6 +1,9 @@
-from .main import Map, Device
-from .read import read
-from .write import write
+from .main import (
+    Map as Map,
+    Device as Device,
+    )
+from .read import read as read
+from .write import write as write
 
 __author__ = 'Jan Petykiewicz'
-__version__ = '0.6'
+__version__ = '0.7'
diff --git a/g85/read.py b/g85/read.py
index 9fd2317..8c4a924 100644
--- a/g85/read.py
+++ b/g85/read.py
@@ -58,22 +58,24 @@ def read_devices(el_map: ElementTree.Element) -> list[Device]:
 
         device = Device(BinType=bin_type, NullBin=null_bin)
 
-        val: Any
         for key, val in el_device.attrib.items():
             if key in ('BinType', 'NullBin'):
                 continue
 
+            parsed_val: Any
             if key in ('WaferSize', 'DeviceSizeX', 'DeviceSizeY', 'Orientation'):
-                val = float(val)
+                parsed_val = float(val)
             elif key in ('OriginLocation',):
-                val = int(val)
+                parsed_val = int(val)
             elif key == 'CreateDate':
-                val = datetime.datetime.strptime(val + '000', '%Y%m%d%H%M%S%f')
+                parsed_val = datetime.datetime.strptime(val + '000', '%Y%m%d%H%M%S%f')
+            else:
+                parsed_val = val
 
             if key in dev_fields and key[0].isupper():
-                setattr(device, key, val)
+                setattr(device, key, parsed_val)
             else:
-                device.misc[key] = val
+                device.misc[key] = parsed_val
 
         for el_entry in el_device:
             tag = _tag(el_entry)
@@ -137,7 +139,7 @@ def read_row(el_row: ElementTree.Element) -> list[str]:
 
 
 def _tag(element: ElementTree.Element) -> str:
-    '''
+    """
     Get the element's tag, excluding any namespaces.
-    '''
+    """
     return element.tag.split('}')[-1]
diff --git a/g85/write.py b/g85/write.py
index 06d4726..e0c0bd3 100644
--- a/g85/write.py
+++ b/g85/write.py
@@ -1,4 +1,5 @@
-from typing import Sequence, TextIO, cast
+from typing import TextIO, cast
+from collections.abc import Sequence
 import logging
 import math
 from dataclasses import fields
@@ -10,12 +11,15 @@ from .main import Map, Device
 logger = logging.getLogger(__name__)
 
 
+class G85Error(Exception):
+    pass
+
+
 # Hack to directly pass through <![CDATA[...]]>
-def _escape_cdata(text):
+def _escape_cdata(text: str) -> str:
     if text.startswith('<![CDATA[') and text.endswith(']]>'):
         return text
-    else:
-        return _original_escape_cdata(text)
+    return _original_escape_cdata(text)
 
 
 _original_escape_cdata = ElementTree._escape_cdata      # type: ignore
@@ -64,7 +68,7 @@ def write_devices(devices: Sequence[Device], el_map: ElementTree.Element) -> Non
 
         # Row data prep
         if device.map is None:
-            raise Exception(f'No _data for device pformat({device})')
+            raise G85Error(f'No _data for device pformat({device})')
 
         is_decimal = device.BinType == 'Decimal'
         row_texts, bin_length = prepare_data(device.map, decimal=is_decimal)
@@ -136,7 +140,7 @@ def prepare_data(data: list[list[str]] | list[list[int]], decimal: bool) -> tupl
                 row_text = ' '.join(srow) + ' '
             row_texts.append(row_text)
         return row_texts, char_len
-    else:
+    else:       # noqa: RET505
         data = cast(list[list[int]], data)
         max_value = max(max(rr) for rr in data)
         max_digits = math.ceil(math.log10(max_value))
diff --git a/pyproject.toml b/pyproject.toml
index 3d9e1e2..3aef2fb 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,8 +38,41 @@ classifiers = [
 requires-python = ">=3.10"
 dynamic = ["version"]
 dependencies = [
-    "numpy~=1.21",
     ]
 
 [tool.hatch.version]
 path = "g85/__init__.py"
+
+
+[tool.ruff]
+exclude = [
+    ".git",
+    "dist",
+    ]
+line-length = 145
+indent-width = 4
+lint.dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"
+lint.select = [
+    "NPY", "E", "F", "W", "B", "ANN", "UP", "SLOT", "SIM", "LOG",
+    "C4", "ISC", "PIE", "PT", "RET", "TCH", "PTH", "INT",
+    "ARG", "PL", "R", "TRY",
+    "G010", "G101", "G201", "G202",
+    "Q002", "Q003", "Q004",
+    ]
+lint.ignore = [
+    #"ANN001",   # No annotation
+    "ANN002",   # *args
+    "ANN003",   # **kwargs
+    "ANN401",   # Any
+    "ANN101",   # self: Self
+    "SIM108",   # single-line if / else assignment
+    "RET504",   # x=y+z; return x
+    "PIE790",   # unnecessary pass
+    "ISC003",   # non-implicit string concatenation
+    "C408",     # dict(x=y) instead of {'x': y}
+    "PLR09",    # Too many xxx
+    "PLR2004",  # magic number
+    "PLC0414",  # import x as x
+    "TRY003",   # Long exception message
+    ]
+