diff --git a/.gitignore b/.gitignore
index 7f368fc..50efb09 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,9 +6,9 @@
 dist/
 *~
 .tox/
-nosetests.xml
 hypatia/coverage.xml
-distribute-*.gz
+coverage-py*.xml
+coverage.xml
 env*/
 .build/
 bin/
diff --git a/.travis.yml b/.travis.yml
index 5dc7023..87049a5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,10 +6,6 @@ matrix:
     include:
         - python: 2.7
           env: TOXENV=py27
-        - python: 3.4
-          env: TOXENV=py34
-        - python: 3.5
-          env: TOXENV=py35
         - python: 3.6
           env: TOXENV=py36
         - python: 3.7
diff --git a/CHANGES.rst b/CHANGES.rst
index fa3f02b..617c2e4 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,9 +1,25 @@
 0.4 (unreleased)
 ----------------
 
-- Add support for Python 3.5.
+- Drop (unreleased) support for Python 3.3 and Python 3.4 (the ``persistent``
+  package no longer supports these versions).
 
-- Drop support for Python 2.6 and 3.2.
+- Drop (unreleased) support for Python 3.5 (too difficult to build correctly --
+  even with pyenv -- to bother).
+
+- Drop (released) support for Python 2.6 and 3.2.
+
+- Add support for Python 3.6, 3.7, 3.8, 3.9, 3.10 (thanks to Thierry Florac).
+
+- Use pytest instead of python setup.py test -q in tox.ini.
+
+- Change how cross-version coverage is computed in tests.
+
+- Remove unused hypatia/text/ricecode.py file.
+
+- Change building of docs slightly to cope with modified github protocols.
+  Some warnings are unearthed with newer Sphinx, which I've not
+  caught by turning warnings into errors yet, because I don't understand them.
 
 - Don't modify queries attribute when optimizing And or Or, return a new
   instance instead. This change is needed to open new optimization
diff --git a/docs/changes.rst b/docs/changes.rst
index 3b92413..ba112b9 100644
--- a/docs/changes.rst
+++ b/docs/changes.rst
@@ -1,4 +1,4 @@
 :mod:`hypatia` Change History
 =============================
 
-.. literalinclude:: ../CHANGES.txt
+.. include:: ../CHANGES.rst
diff --git a/docs/conf.py b/docs/conf.py
index d2b6061..23cbddf 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -27,7 +27,7 @@
     _themes = os.path.join(cwd, '_themes')
 
     if not os.path.isdir(_themes):
-        call([git, 'clone', 'git://github.com/Pylons/pylons_sphinx_theme.git',
+        call([git, 'clone', 'https://github.com/Pylons/pylons_sphinx_theme.git',
                 '_themes'])
     else:
         os.chdir(_themes)
diff --git a/hypatia/text/ricecode.py b/hypatia/text/ricecode.py
deleted file mode 100644
index a7c60da..0000000
--- a/hypatia/text/ricecode.py
+++ /dev/null
@@ -1,214 +0,0 @@
-##############################################################################
-#
-# Copyright (c) 2002 Zope Foundation and Contributors.
-# All Rights Reserved.
-#
-# This software is subject to the provisions of the Zope Public License,
-# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
-# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
-# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
-# FOR A PARTICULAR PURPOSE.
-#
-##############################################################################
-"""Rice coding (a variation of Golomb coding)
-
-Based on a Java implementation by Glen McCluskey described in a Usenix
- ;login: article at
-http://www.usenix.org/publications/login/2000-4/features/java.html
-
-McCluskey's article explains the approach as follows.  The encoding
-for a value x is represented as a unary part and a binary part.  The
-unary part is a sequence of 1 bits followed by a 0 bit.  The binary
-part encodes some of the lower bits of x-1.
-
-The encoding is parameterized by a value m that describes how many
-bits to store in the binary part.  If most of the values are smaller
-than 2**m then they can be stored in only m+1 bits.
-
-Compute the length of the unary part, q, where
-   q = math.floor((x-1)/ 2 ** m)
-
-   Emit q 1 bits followed by a 0 bit.
-
-Emit the lower m bits of x-1, treating x-1 as a binary value.
-"""
-
-import array
-
-class BitArray(object):
-
-    def __init__(self, buf=None):
-        self.bytes = array.array('B')
-        self.nbits = 0
-        self.bitsleft = 0
-        self.tostring = self.bytes.tostring
-
-    def __getitem__(self, i):
-        byte, offset = divmod(i, 8)
-        mask = 2 ** offset
-        if self.bytes[byte] & mask:
-            return 1
-        else:
-            return 0
-
-    def __setitem__(self, i, val):
-        byte, offset = divmod(i, 8)
-        mask = 2 ** offset
-        if val:
-            self.bytes[byte] |= mask
-        else:
-            self.bytes[byte] &= ~mask
-
-    def __len__(self):
-        return self.nbits
-
-    def append(self, bit):
-        """Append a 1 if bit is true or 1 if it is false."""
-        if self.bitsleft == 0:
-            self.bytes.append(0)
-            self.bitsleft = 8
-        self.__setitem__(self.nbits, bit)
-        self.nbits += 1
-        self.bitsleft -= 1
-
-    def __getstate__(self):
-        return self.nbits, self.bitsleft, self.tostring()
-
-    def __setstate__(self, nbits_bitsleft_s):
-        nbits, bitsleft, s = nbits_bitsleft_s
-        self.bytes = array.array('B', s)
-        self.nbits = nbits
-        self.bitsleft = bitsleft
-
-class RiceCode(object):
-    def __init__(self, m):
-        """Constructor a RiceCode for m-bit values."""
-        if not (0 <= m <= 16):
-            raise ValueError("m must be between 0 and 16")
-        self.init(m)
-        self.bits = BitArray()
-        self.len = 0
-
-    def init(self, m):
-        self.m = m
-        self.lower = (1 << m) - 1
-        self.mask = 1 << (m - 1)
-
-    def append(self, val):
-        """Append an item to the list."""
-        if val < 1:
-            raise ValueError("value >= 1 expected, got %s" % repr(val))
-        val -= 1
-        # emit the unary part of the code
-        q = val >> self.m
-        for i in range(q):
-            self.bits.append(1)
-        self.bits.append(0)
-        # emit the binary part
-        r = val & self.lower
-        mask = self.mask
-        while mask:
-            self.bits.append(r & mask)
-            mask >>= 1
-        self.len += 1
-
-    def __len__(self):
-        return self.len
-
-    def tolist(self):
-        """Return the items as a list."""
-        l = []
-        i = 0 # bit offset
-        binary_range = range(self.m)
-        for j in range(self.len):
-            unary = 0
-            while self.bits[i] == 1:
-                unary += 1
-                i += 1
-            assert self.bits[i] == 0
-            i += 1
-            binary = 0
-            for k in binary_range:
-                binary = (binary << 1) | self.bits[i]
-                i += 1
-            l.append((unary << self.m) + (binary + 1))
-        return l
-
-    def tostring(self):
-        """Return a binary string containing the encoded data.
-
-        The binary string may contain some extra zeros at the end.
-        """
-        return self.bits.tostring()
-
-    def __getstate__(self):
-        return self.m, self.bits
-
-    def __setstate__(self, m_bits):
-        m, bits = m_bits
-        self.init(m)
-        self.bits = bits
-
-def encode(m, l):
-    c = RiceCode(m)
-    for elt in l:
-        c.append(elt)
-    assert c.tolist() == l
-    return c
-
-def encode_deltas(l):
-    if len(l) == 1:
-        return l[0], []
-    deltas = RiceCode(6)
-    deltas.append(l[1] - l[0])
-    for i in range(2, len(l)):
-        deltas.append(l[i] - l[i - 1])
-    return l[0], deltas
-
-def decode_deltas(start, enc_deltas):
-    deltas = enc_deltas.tolist()
-    l = [start]
-    for i in range(1, len(deltas)):
-        l.append(l[i-1] + deltas[i])
-    l.append(l[-1] + deltas[-1])
-    return l
-
-def _print(x, newline=True):
-    import sys
-    fmt = newline and '%s\n' or '%s'
-    sys.stdout.write(fmt % x)
-
-def test():
-    import random
-    for size in [10, 20, 50, 100, 200]:
-        l = [random.randint(1, size) for i in range(50)]
-        c = encode(random.randint(1, 16), l)
-        assert c.tolist() == l
-    for size in [10, 20, 50, 100, 200]:
-        l = range(random.randint(1, size), size + random.randint(1, size))
-        t = encode_deltas(l)
-        l2 = decode_deltas(*t)
-        assert l == l2
-        if l != l2:
-            _print(l)
-            _print(l2)
-
-def pickle_efficiency():
-    import pickle
-    import random
-    for m in [4, 8, 12]:
-        for size in [10, 20, 50, 100, 200, 500, 1000, 2000, 5000]:
-            for elt_range in [10, 20, 50, 100, 200, 500, 1000]:
-                l = [random.randint(1, elt_range) for i in range(size)]
-                raw = pickle.dumps(l, 1)
-                enc = pickle.dumps(encode(m, l), 1)
-                _print("m=%2d size=%4d range=%4d" % (m, size, elt_range), False)
-                _print("%5d %5d" % (len(raw), len(enc)), False)
-                if len(raw) > len(enc):
-                    _print("win")
-                else:
-                    _print("lose")
-
-if __name__ == "__main__":
-    test()
diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 0000000..92d5165
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,4 @@
+[pytest]
+python_files = test*.py
+addopts = --deselect=hypatia/tests/test_functional.py::TestCatalogQueryBase
+
diff --git a/setup.py b/setup.py
index bead19e..ce649d3 100644
--- a/setup.py
+++ b/setup.py
@@ -70,8 +70,12 @@ def errprint(x):
     'zope.interface',
     ]
 
-testing_extras = ['nose', 'coverage', 'nosexcover']
-docs_extras = ['Sphinx']
+testing_extras = ['pytest', 'coverage']
+
+docs_extras = [
+    'Sphinx >= 3.0.0',  # Force RTD to use >= 3.0.0
+]
+
 
 setup(name='hypatia',
       version='0.4.dev0',
@@ -83,8 +87,6 @@ def errprint(x):
         "Programming Language :: Python :: 2",
         "Programming Language :: Python :: 2.7",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.4",
-        "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
diff --git a/tox.ini b/tox.ini
index 5ced065..dee35fd 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,26 +1,55 @@
 [tox]
 envlist = 
-    py27,py34,py35,py36,py37,py38,py39,py310,cover,docs
+    py27,py36,py37,py38,py39,py310,{py2,py3}-cover,coverage,docs
 
 [testenv]
 commands = 
-    python setup.py -q test -q
+    pip install -e .[testing]
+    pytest
+extras =
+    testing
 
-[testenv:cover]
-basepython =
-    python3.9
-commands = 
-    pip install hypatia[testing]
-    nosetests --with-xunit --with-xcoverage
+[testenv:py2-cover]
+basepython = python2.7
+commands =
+    #coverage run setup.py -q test -q
+    pip install -e .[testing]
+    coverage run --source=hypatia {envbindir}/pytest
+    coverage xml -o coverage-py2.xml
+setenv =
+    COVERAGE_FILE=.coverage.py2
+extras =
+    testing
 
-# we separate coverage into its own testenv because a) "last run wins" wrt
-# cobertura jenkins reporting and b) pypy and jython can't handle any
-# combination of versions of coverage and nosexcover that i can find.
+[testenv:py3-cover]
+basepython = python3.10
+commands =
+    #coverage run setup.py -q test -q
+    pip install -e .[testing]
+    coverage run --source=hypatia {envbindir}/pytest
+    coverage xml -o coverage-py3.xml
+setenv =
+    COVERAGE_FILE=.coverage.py3
+extras =
+    testing
 
-[testenv:docs]
+[testenv:coverage]
 basepython =
-    python3.9
-commands = 
-    sphinx-build -b html -d docs/_build/doctrees docs docs/_build/html
+    python2.7
+skip_install = true
+commands =
+    coverage erase
+    coverage combine
+    coverage xml
+    coverage report -m --fail-under=100
 deps =
-    Sphinx
+    coverage
+setenv =
+    COVERAGE_FILE=.coverage
+
+[testenv:docs]
+whitelist_externals = make
+commands =
+    make -C docs {posargs:html} BUILDDIR={envdir} "SPHINXOPTS=-E"
+extras =
+    docs