diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bb242ba8..da9c3545 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -69,7 +69,7 @@ jobs:
         run: |
           python -m pip install -U pip setuptools wheel pybind11
           cat requirements.txt
-          python -m pip install -r requirements.txt --prefer-binary
+          python -m pip install -r requirements.txt --prefer-binary --no-build-isolation
           python -m pip install coveralls
 
       - name: Setup annotations on Linux
@@ -254,11 +254,12 @@ jobs:
             /var/cache/dnf/
           key: ${{ runner.os }}-centos${{ matrix.centos }}-yum-${{ secrets.yum_cache }}
 
-      - name: Fix repository URLs (CentOS 8 only)
-        if: matrix.centos == 8
+      - name: Fix repository URLs
         run: |
           sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
           sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*
+          sed -i 's|mirror.centos.org|vault.centos.org|g' /etc/yum.repos.d/CentOS-*
+          sed -i 's|^#baseurl|baseurl|g' /etc/yum.repos.d/CentOS-*
 
       - name: Update YUM/DNF
         run: yum update -y
@@ -267,6 +268,9 @@ jobs:
         if: matrix.centos == 7
         run: |
           yum install -y centos-release-scl-rh
+          sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
+          sed -i 's|mirror.centos.org|vault.centos.org|g' /etc/yum.repos.d/CentOS-*
+          sed -i 's|^#baseurl|baseurl|g' /etc/yum.repos.d/CentOS-*
           yum -y install https://packages.endpointdev.com/rhel/7/os/x86_64/endpoint-repo.x86_64.rpm
           echo '/opt/rh/rh-python38/root/usr/bin' >> $GITHUB_PATH
 
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index 18a5a10c..5f462e8a 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -30,9 +30,10 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Prepare env
-        run: >
-          apt-get update && apt-get install -y python3-dev python3-pip python3-setuptools python3-wheel
-          --no-install-recommends
+        run: |
+          sed -i 's|deb.debian.org/debian-security|archive.debian.org/debian-security|g' /etc/apt/sources.list
+          apt-get update -o Acquire::Retries=3
+          apt-get install -y python3-dev python3-pip python3-setuptools python3-wheel --no-install-recommends
 
       - name: Upgrade pybind11 and setuptools
         run: python3 -m pip install --upgrade pybind11 "setuptools>=61.0.0" --prefer-binary
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e58e1202..c80cf3ef 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 -   Fixed some typos (thanks to @eltociear, @Darkdragon84)
 -   Fixed support for Python 3.12
+-   Fixed `ComparatorQuantum` decomposition so input registers are properly restored (#491)
 
 ### Removed
 
@@ -23,6 +24,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Repository
 
 -   Update GitHub workflows to work with merge queues
+-   Fix Clang-Tidy Debian security package source URL in GitHub workflow
+-   Fix setuptools >= 70 compatibility in compiler configuration and build commands
 -   Update GitHub workflow action versions: `actions/cache@v3`, `actions/checkout@v3`, `actions/setup-python@v4`, `thomaseizinger/create-pull-request`
 -   Update pre-commit hook versions
 -   Fix failing GitHub workflows (Clang-10)
diff --git a/projectq/libs/math/_quantummath.py b/projectq/libs/math/_quantummath.py
index 59aa7cf9..8a984951 100644
--- a/projectq/libs/math/_quantummath.py
+++ b/projectq/libs/math/_quantummath.py
@@ -218,11 +218,11 @@ def comparator(eng, quint_a, quint_b, comp):
     with Control(eng, [quint_a[n_qubits - 2], quint_b[n_qubits - 2]]):
         X | comp
 
-    for k in range(0, n_qubits - 2):
+    for k in range(n_qubits - 3, -1, -1):
         with Control(eng, [quint_a[k], quint_b[k]]):
             X | (quint_a[k + 1])
 
-    for j in range(n_qubits - 3, 0, -1):
+    for j in range(1, n_qubits - 2):
         CNOT | (quint_a[j], quint_a[j + 1])
 
     for i in range(1, n_qubits - 1):
diff --git a/projectq/libs/math/_quantummath_test.py b/projectq/libs/math/_quantummath_test.py
index d32715ca..810b54a3 100644
--- a/projectq/libs/math/_quantummath_test.py
+++ b/projectq/libs/math/_quantummath_test.py
@@ -17,7 +17,12 @@
 import projectq.libs.math
 from projectq import MainEngine
 from projectq.backends import Simulator
-from projectq.cengines import AutoReplacer, DecompositionRuleSet, InstructionFilter
+from projectq.cengines import (
+    AutoReplacer,
+    BasicEngine,
+    DecompositionRuleSet,
+    InstructionFilter,
+)
 from projectq.libs.math import (
     AddQuantum,
     ComparatorQuantum,
@@ -249,6 +254,8 @@ def test_comparator(eng):
 
     ComparatorQuantum | (qureg_a, qureg_b, compare_qubit)
 
+    assert 1.0 == pytest.approx(eng.backend.get_probability([1, 0, 1], qureg_a))
+    assert 1.0 == pytest.approx(eng.backend.get_probability([1, 1, 0], qureg_b))
     assert 1.0 == pytest.approx(eng.backend.get_probability([1], compare_qubit))
 
     # Size mismatch in qubit registers
@@ -264,6 +271,85 @@ def test_comparator(eng):
     Measure | compare_qubit
 
 
+class _BasisBackend(BasicEngine):
+    """Exact basis-state backend accepting only multi-controlled X and lifecycle gates."""
+
+    def __init__(self):
+        super().__init__()
+        self.state = {}
+
+    def is_available(self, cmd):
+        return cmd.gate.__class__.__name__ in (
+            'XGate',
+            'AllocateQubitGate',
+            'DeallocateQubitGate',
+            'FlushGate',
+            'MeasureGate',
+        )
+
+    def receive(self, commands):
+        for cmd in commands:
+            name = cmd.gate.__class__.__name__
+            if name == 'AllocateQubitGate':
+                self.state[cmd.qubits[0][0].id] = 0
+            elif name == 'XGate' and all(self.state[c.id] for c in cmd.control_qubits):
+                self.state[cmd.qubits[0][0].id] ^= 1
+
+
+def _run_comparator_decomposition(a_val, b_val, c_val, n_bits=3):
+    backend = _BasisBackend()
+    rules = DecompositionRuleSet(modules=[projectq.libs.math])
+    engine = MainEngine(backend=backend, engine_list=[AutoReplacer(rules)])
+    reg_a = engine.allocate_qureg(n_bits)
+    reg_b = engine.allocate_qureg(n_bits)
+    reg_c = engine.allocate_qureg(1)
+    for i, qubit in enumerate(reg_a):
+        if (a_val >> i) & 1:
+            X | qubit
+    for i, qubit in enumerate(reg_b):
+        if (b_val >> i) & 1:
+            X | qubit
+    if c_val:
+        X | reg_c[0]
+    ComparatorQuantum | (reg_a, reg_b, reg_c)
+    All(Measure) | (reg_a + reg_b + reg_c)
+    engine.flush()
+    res_a = sum(backend.state[q.id] << i for i, q in enumerate(reg_a))
+    res_b = sum(backend.state[q.id] << i for i, q in enumerate(reg_b))
+    res_c = backend.state[reg_c[0].id]
+    return res_a, res_b, res_c
+
+
+@pytest.mark.parametrize(
+    'a, b, c_in, expected_c',
+    [
+        (1, 0, 0, 1),
+        (0, 1, 0, 0),
+        (2, 2, 0, 0),
+        (1, 0, 1, 0),
+        (0, 1, 1, 1),
+        (7, 0, 0, 1),
+        (0, 7, 0, 0),
+        (7, 7, 1, 1),
+    ],
+)
+def test_comparator_decomposition_restore_registers(a, b, c_in, expected_c):
+    res_a, res_b, res_c = _run_comparator_decomposition(a, b, c_in, n_bits=3)
+    assert res_a == a
+    assert res_b == b
+    assert res_c == expected_c
+
+
+def test_comparator_decomposition_all_3bit_cases():
+    for a in range(8):
+        for b in range(8):
+            for c_in in (0, 1):
+                res_a, res_b, res_c = _run_comparator_decomposition(a, b, c_in, n_bits=3)
+                assert res_a == a
+                assert res_b == b
+                assert res_c == c_in ^ int(a > b)
+
+
 @pytest.mark.parametrize('qubit_idx', (0, 1, 2))
 def test_quantumdivision_size_mismatch(eng, qubit_idx):
     qureg_a = eng.allocate_qureg(4 if qubit_idx != 0 else 3)
diff --git a/pyproject.toml b/pyproject.toml
index 6e4686e2..19d426db 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,7 +31,7 @@ dynamic = ["version"]
 dependencies = [
     'matplotlib >= 2.2.3',
     'networkx >= 2.4',
-    'numpy>=1.21.5',
+    'numpy>=1.21.5, <2',
     'requests>=2.25.1',
     'scipy>=1.8.0'
 ]
@@ -44,7 +44,7 @@ dependencies = [
 [project.optional-dependencies]
 
 azure-quantum = [
-      'azure-quantum'
+      'azure-quantum < 3.10'
 ]
 
 braket = [
diff --git a/setup.py b/setup.py
index 24a647bd..74104658 100755
--- a/setup.py
+++ b/setup.py
@@ -429,8 +429,9 @@ def _get_compilation_commands(self, ext):
 
     def _configure_compiler(self):
         # Force dry_run = False to allow for compiler feature testing
-        dry_run_old = self.compiler.dry_run
-        self.compiler.dry_run = False
+        dry_run_old = getattr(self.compiler, 'dry_run', False)
+        if hasattr(self.compiler, 'dry_run'):
+            self.compiler.dry_run = False
 
         if (
             int(os.environ.get('PROJECTQ_CLEANUP_COMPILER_FLAGS', 0))
@@ -472,7 +473,8 @@ def _configure_compiler(self):
         if compiler_type == 'unix' and compiler_test(self.compiler, '-fvisibility=hidden'):
             self.opts.append('-fvisibility=hidden')
 
-        self.compiler.dry_run = dry_run_old
+        if hasattr(self.compiler, 'dry_run'):
+            self.compiler.dry_run = dry_run_old
         status_msgs('Finished configuring compiler!')
 
     def _configure_openmp(self):
@@ -680,7 +682,8 @@ def run(self):
             command.append('--warnings-as-errors=*')
         for ext in self.distribution.ext_modules:
             command.extend(os.path.abspath(p) for p in ext.sources)
-        spawn(command, dry_run=self.dry_run)
+        if not self.dry_run:
+            spawn(command)
 
 
 # ------------------------------------------------------------------------------