diff --git a/.gitignore b/.gitignore
index e07fb7c..c4a80f8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,3 +13,4 @@
 
 dist
 build
+/*.egg-info
diff --git a/__init__.py b/colorpy/__init__.py
similarity index 100%
rename from __init__.py
rename to colorpy/__init__.py
diff --git a/blackbody.py b/colorpy/blackbody.py
similarity index 100%
rename from blackbody.py
rename to colorpy/blackbody.py
diff --git a/ciexyz.py b/colorpy/ciexyz.py
similarity index 100%
rename from ciexyz.py
rename to colorpy/ciexyz.py
diff --git a/colormodels.py b/colorpy/colormodels.py
similarity index 100%
rename from colormodels.py
rename to colorpy/colormodels.py
diff --git a/figures.py b/colorpy/figures.py
similarity index 100%
rename from figures.py
rename to colorpy/figures.py
diff --git a/illuminants.py b/colorpy/illuminants.py
similarity index 100%
rename from illuminants.py
rename to colorpy/illuminants.py
diff --git a/misc.py b/colorpy/misc.py
similarity index 100%
rename from misc.py
rename to colorpy/misc.py
diff --git a/plots.py b/colorpy/plots.py
similarity index 100%
rename from plots.py
rename to colorpy/plots.py
diff --git a/rayleigh.py b/colorpy/rayleigh.py
similarity index 100%
rename from rayleigh.py
rename to colorpy/rayleigh.py
diff --git a/thinfilm.py b/colorpy/thinfilm.py
similarity index 100%
rename from thinfilm.py
rename to colorpy/thinfilm.py
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..a5aa0a0
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,33 @@
+[build-system]
+requires = ["setuptools>=61.2"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "colorpy"
+version = "0.1.1"
+authors = [{name = "Mark Kness", email = "mkness@alumni.utexas.net"}]
+license = {text = "LGPL-3.0-or-later"}
+description = "Color calculations with physical descriptions of light spectra"
+
+[project.readme]
+text = "ColorPy is a Python package to convert physical descriptions of light spectra of light intensity vs. wavelength - into RGB colors that can be drawn on a computer screen. It provides a nice set of attractive plots that you can make of such spectra, and some other color related functions as well."
+content-type = "text/plain"
+
+[project.urls]
+Homepage = "http://markkness.net/colorpy/"
+"Source Code" = "https://github.com/fish2000/colorpy"
+"Issue Tracker" = "https://github.com/fish2000/colorpy/issues"
+
+[tool.setuptools]
+package-dir = {colorpy = "."}
+packages = ["colorpy"]
+include-package-data = false
+
+[tool.setuptools.package-data]
+colorpy = [
+    "README.rst",
+    "COPYING.txt",
+    "COPYING.LESSER.txt",
+    "license.txt",
+    "ColorPy.html",
+]
diff --git a/setup.py b/setup.py
deleted file mode 100755
index 38cdc3a..0000000
--- a/setup.py
+++ /dev/null
@@ -1,49 +0,0 @@
-#!/usr/bin/env python
-'''
-setup.py - Setup script to install the ColorPy package.
-
-To install the ColorPy package:
-From the directory in which the ColorPy distribution was unpacked, run:
-
-python setup.py install
-
-You should now be able to say 'import colorpy' in your programs and use the package.
-
-Creating the distribution:
-
-python setup.py sdist --formats=zip
-python setup.py sdist --formats=gztar
-python setup.py bdist_wininst
-'''
-
-from distutils.core import setup
-
-data_files = [
-    'README.rst',
-    'COPYING.txt',
-    'COPYING.LESSER.txt',
-    'license.txt',
-    'ColorPy.html',
-]
-
-long_description = '''
-ColorPy is a Python package to convert physical descriptions of light -
-    spectra of light intensity vs. wavelength - into RGB colors that can
-    be drawn on a computer screen.
-    It provides a nice set of attractive plots that you can make of such
-    spectra, and some other color related functions as well.
-'''
-
-setup (
-    name='colorpy',
-    version='0.1.1',
-    description='Color calculations with physical descriptions of light spectra',
-    long_description=long_description,
-    author='Mark Kness',
-    author_email='mkness@alumni.utexas.net',
-    url='http://markkness.net/colorpy/',
-    license='GNU Lesser GPL Version 3',
-    package_dir={'colorpy': '.'},
-    packages=['colorpy'],
-    package_data={'colorpy': data_files},
-)
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/test.py b/tests/__main__.py
similarity index 97%
rename from test.py
rename to tests/__main__.py
index b4fc98c..8b374f3 100755
--- a/test.py
+++ b/tests/__main__.py
@@ -40,5 +40,6 @@ def test ():
     test_blackbody.test()
     test_rayleigh.test()
     test_thinfilm.test()
-    
-    
+
+if __name__ == "__main__":
+    test()
diff --git a/test_blackbody.py b/tests/test_blackbody.py
similarity index 99%
rename from test_blackbody.py
rename to tests/test_blackbody.py
index a7bb481..07e7076 100755
--- a/test_blackbody.py
+++ b/tests/test_blackbody.py
@@ -26,7 +26,7 @@
 
 import math, random, numpy
 
-from . import colormodels, blackbody
+from colorpy import colormodels, blackbody
 
 STEFAN_BOLTZMAN = 5.670e-8        # W/(m^2 K^4)
 
diff --git a/test_ciexyz.py b/tests/test_ciexyz.py
similarity index 98%
rename from test_ciexyz.py
rename to tests/test_ciexyz.py
index d886943..2ca1c13 100755
--- a/test_ciexyz.py
+++ b/tests/test_ciexyz.py
@@ -26,7 +26,7 @@
 
 import random
 
-from . import ciexyz
+from colorpy import ciexyz
 
 def test (verbose=0):
     '''Test the CIE XYZ conversions.  Mainly call some functions.'''
diff --git a/test_colormodels.py b/tests/test_colormodels.py
similarity index 99%
rename from test_colormodels.py
rename to tests/test_colormodels.py
index 9365012..84604bf 100755
--- a/test_colormodels.py
+++ b/tests/test_colormodels.py
@@ -25,7 +25,7 @@
 from __future__ import division, absolute_import, print_function
 
 import math, random, numpy
-from . import colormodels, ciexyz
+from colorpy import colormodels, ciexyz
 
 def test_xyz_rgb (verbose=1):
     '''Test that xyz_to_rgb() and rgb_to_xyz() are inverses.'''
diff --git a/test_illuminants.py b/tests/test_illuminants.py
similarity index 98%
rename from test_illuminants.py
rename to tests/test_illuminants.py
index 2543d9b..36f8f7b 100755
--- a/test_illuminants.py
+++ b/tests/test_illuminants.py
@@ -24,7 +24,7 @@
 '''
 from __future__ import division, absolute_import, print_function
 
-from . import illuminants
+from colorpy import illuminants
 
 def test (verbose=0):
     '''Mainly call some functions.'''
diff --git a/test_rayleigh.py b/tests/test_rayleigh.py
similarity index 96%
rename from test_rayleigh.py
rename to tests/test_rayleigh.py
index 6ade594..03295fe 100755
--- a/test_rayleigh.py
+++ b/tests/test_rayleigh.py
@@ -26,7 +26,7 @@
 
 import random
 
-from . import rayleigh, illuminants
+from colorpy import rayleigh, illuminants
 
 def test ():
     '''Mainly call some functions.'''
diff --git a/test_thinfilm.py b/tests/test_thinfilm.py
similarity index 97%
rename from test_thinfilm.py
rename to tests/test_thinfilm.py
index 3142769..f824953 100755
--- a/test_thinfilm.py
+++ b/tests/test_thinfilm.py
@@ -26,7 +26,7 @@
 
 import random
 
-from . import illuminants, thinfilm
+from colorpy import illuminants, thinfilm
 
 def test ():
     '''Module test.  Mainly call some functions.'''