diff --git a/src/diffpy/pdfgui/control/pdfguicontrol.py b/src/diffpy/pdfgui/control/pdfguicontrol.py
@@ -89,7 +89,7 @@ def run(self):
 
     def startQueue(self):
         """start queue manager"""
-        self.queueManager.setDaemon(True)
+        self.queueManager.daemon = True
         self.queueManager.start()
 
     def checkQueue(self):

diff --git a/src/diffpy/pdfgui/gui/extendedplotframe.py b/src/diffpy/pdfgui/gui/extendedplotframe.py
@@ -368,9 +368,9 @@ def legendBoxProperties():
         return _lbp
     #  figure out matplotlib version and appropriate names
     from matplotlib import __version__ as mplver
-    from pkg_resources import parse_version
+    from packaging.version import parse
 
-    if parse_version(mplver) >= parse_version("0.98.5"):
+    if parse(mplver) >= parse("0.98.5"):
         _lbp = {
             "loc": "upper right",
             "numpoints": 3,  # number of points in the legend line

diff --git a/src/diffpy/pdfgui/gui/pdfguiglobals.py b/src/diffpy/pdfgui/gui/pdfguiglobals.py
@@ -16,8 +16,7 @@
 """This module contains global parameters needed by PDFgui."""
 
 import os.path
-
-from pkg_resources import Requirement, resource_filename
+from importlib.resources import files
 
 from diffpy.pdfgui.gui import debugoptions
 
@@ -31,23 +30,23 @@
 isAltered = False
 
 # Resolve APPDATADIR base path to application data files.
-_mydir = os.path.abspath(resource_filename(__name__, ""))
+_mydir = os.path.abspath(str(files(__name__)))
 _upbasedir = os.path.normpath(_mydir + "/../../..")
 _development_mode = os.path.basename(_upbasedir) == "src" and os.path.isfile(
-    os.path.join(_upbasedir, "../setup.py")
+    os.path.join(_upbasedir, "../pyproject.toml")
 )
 
 # Requirement must have egg-info.  Do not use in _development_mode.
-_req = Requirement.parse("diffpy.pdfgui")
+_req = "diffpy.pdfgui"
 
 # pavol
 # APPDATADIR = (os.path.dirname(_upbasedir) if _development_mode
-#               else resource_filename(_req, ""))
+#               else str(files(_req)))
 # long
 if _development_mode:
     APPDATADIR = os.path.dirname(_mydir)
 else:
-    APPDATADIR = os.path.join(resource_filename(_req, ""), "diffpy/pdfgui")
+    APPDATADIR = str(files(_req))
 
 APPDATADIR = os.path.abspath(APPDATADIR)
 

diff --git a/src/diffpy/pdfgui/tests/__init__.py b/src/diffpy/pdfgui/tests/__init__.py
@@ -35,13 +35,12 @@ def testsuite(pattern=""):
         The TestSuite object containing the matching tests.
     """
     import re
+    from importlib.resources import files
     from itertools import chain
     from os.path import dirname
 
-    from pkg_resources import resource_filename
-
     loader = unittest.defaultTestLoader
-    thisdir = resource_filename(__name__, "")
+    thisdir = str(files(__name__))
     depth = __name__.count(".") + 1
     topdir = thisdir
     for i in range(depth):

diff --git a/src/diffpy/pdfgui/tests/testutils.py b/src/diffpy/pdfgui/tests/testutils.py
@@ -29,9 +29,9 @@
 
 
 def datafile(filename):
-    from pkg_resources import resource_filename
+    from importlib.resources import files
 
-    rv = resource_filename(__name__, "testdata/" + filename)
+    rv = str(files(__name__).joinpath("testdata", filename))
     return rv
 
 

diff --git a/src/diffpy/pdfgui/version.py b/src/diffpy/pdfgui/version.py
@@ -25,16 +25,15 @@
 __all__ = ["__date__", "__git_commit__", "__timestamp__", "__version__"]
 
 import os.path
-
-from pkg_resources import resource_filename
+from importlib.resources import files
 
 # obtain version information from the version.cfg file
 cp = dict(version="", date="", commit="", timestamp="0")
-fcfg = resource_filename(__name__, "version.cfg")
+fcfg = str(files(__name__).joinpath("version.cfg"))
 if not os.path.isfile(fcfg):  # pragma: no cover
     from warnings import warn
 
-    warn('Package metadata not found, execute "./setup.py egg_info".')
+    warn("Package metadata not found.")
     fcfg = os.devnull
 with open(fcfg) as fp:
     kwords = [[w.strip() for w in line.split(" = ", 1)] for line in fp if line[:1].isalpha() and " = " in line]