diff --git a/.gitignore b/.gitignore
index 048903d6..3d779c37 100644
--- a/.gitignore
+++ b/.gitignore
@@ -27,3 +27,7 @@ pip-log.txt
 
 #Translations
 *.mo
+
+.cargo/
+vendor/
+.pybuild/
diff --git a/debian/.gitignore b/debian/.gitignore
new file mode 100644
index 00000000..59720fda
--- /dev/null
+++ b/debian/.gitignore
@@ -0,0 +1,6 @@
+*.substvars
+*debhelper*
+.debhelper
+files
+python3-bcrypt
+tmp
diff --git a/debian/changelog b/debian/changelog
new file mode 100644
index 00000000..2076b4b4
--- /dev/null
+++ b/debian/changelog
@@ -0,0 +1,5 @@
+python-bcrypt (100:4.2.1-1) UNRELEASED; urgency=medium
+
+  * https://github.com/pyca/bcrypt/releases/tag/4.2.1
+
+ -- Wong Hoi Sing Edison <hswong3i@pantarei-design.com>  Wed, 20 Nov 2024 07:48:29 +0800
diff --git a/debian/control b/debian/control
new file mode 100644
index 00000000..6b16315f
--- /dev/null
+++ b/debian/control
@@ -0,0 +1,31 @@
+Source: python-bcrypt
+Section: python
+Priority: optional
+Standards-Version: 4.5.0
+Maintainer: Wong Hoi Sing Edison <hswong3i@pantarei-design.com>
+Homepage: https://github.com/pyca/bcrypt/tags
+Vcs-Browser: https://github.com/alvistack/pyca-bcrypt
+Vcs-Git: https://github.com/alvistack/pyca-bcrypt.git
+Build-Depends:
+ cargo,
+ cython3,
+ debhelper,
+ debhelper-compat (= 10),
+ dh-python,
+ fdupes,
+ python3-dev,
+ python3-pip,
+ python3-pycparser,
+ python3-setuptools (>= 42.0.0),
+ python3-setuptools-rust (>= 1.7.0),
+ rustc (>= 1.64.0),
+
+Package: python3-bcrypt
+Architecture: amd64
+Description: Modern(-ish) password hashing for your software and your servers
+ Good password hashing for your software and your servers.
+Depends:
+ ${misc:Depends},
+ ${shlibs:Depends},
+ ${python3:Depends},
+ python3,
diff --git a/debian/copyright b/debian/copyright
new file mode 100644
index 00000000..12900b41
--- /dev/null
+++ b/debian/copyright
@@ -0,0 +1,21 @@
+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+
+Files: debian/*
+Copyright: 2024 Wong Hoi Sing Edison <hswong3i@pantarei-design.com>
+License: Apache-2.0
+
+License: Apache-2.0
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+ .
+ http://www.apache.org/licenses/LICENSE-2.0
+ .
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ .
+ The complete text of the Apache version 2.0 license
+ can be found in "/usr/share/common-licenses/Apache-2.0".
diff --git a/debian/python3-bcrypt.install b/debian/python3-bcrypt.install
new file mode 100644
index 00000000..e3da3e75
--- /dev/null
+++ b/debian/python3-bcrypt.install
@@ -0,0 +1 @@
+usr/lib/python*/*-packages/*
diff --git a/debian/python3-bcrypt.lintian-overrides b/debian/python3-bcrypt.lintian-overrides
new file mode 100644
index 00000000..1b0a6375
--- /dev/null
+++ b/debian/python3-bcrypt.lintian-overrides
@@ -0,0 +1,4 @@
+python3-bcrypt: copyright-without-copyright-notice
+python3-bcrypt: initial-upload-closes-no-bugs
+python3-bcrypt: no-manual-page
+python3-bcrypt: zero-byte-file-in-doc-directory
diff --git a/debian/rules b/debian/rules
new file mode 100755
index 00000000..1f63af55
--- /dev/null
+++ b/debian/rules
@@ -0,0 +1,31 @@
+#!/usr/bin/make -f
+
+SHELL := /bin/bash
+
+override_dh_auto_configure:
+
+override_dh_auto_build:
+	pip wheel \
+		--no-deps \
+		--no-build-isolation \
+		--wheel-dir=dist \
+		.
+
+override_dh_auto_install:
+	pip install \
+		--no-deps \
+		--ignore-installed \
+		--root=debian/tmp \
+		--prefix=/usr \
+		dist/*.whl
+	mv debian/tmp/usr/local/* debian/tmp/usr/ || echo $$?
+	rm -rf debian/tmp/usr/local || echo $$?
+	find debian/tmp/usr/lib/python*/*-packages -type f -name '*.pyc' -exec rm -rf {} \;
+	fdupes -qnrps debian/tmp/usr/lib/python*/*-packages
+
+override_dh_auto_test:
+
+override_dh_auto_clean:
+
+%:
+	dh $@ --with python3
diff --git a/debian/source/format b/debian/source/format
new file mode 100644
index 00000000..163aaf8d
--- /dev/null
+++ b/debian/source/format
@@ -0,0 +1 @@
+3.0 (quilt)
diff --git a/debian/source/lintian-overrides b/debian/source/lintian-overrides
new file mode 100644
index 00000000..52ff17b1
--- /dev/null
+++ b/debian/source/lintian-overrides
@@ -0,0 +1,5 @@
+python-bcrypt source: file-without-copyright-information
+python-bcrypt source: no-debian-changes
+python-bcrypt source: source-contains-prebuilt-windows-binary
+python-bcrypt source: source-package-encodes-python-version
+python-bcrypt source: unpack-message-for-orig
diff --git a/python-bcrypt.spec b/python-bcrypt.spec
new file mode 100644
index 00000000..67806dfe
--- /dev/null
+++ b/python-bcrypt.spec
@@ -0,0 +1,103 @@
+# Copyright 2024 Wong Hoi Sing Edison <hswong3i@pantarei-design.com>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+%global debug_package %{nil}
+
+%global source_date_epoch_from_changelog 0
+
+Name: python-bcrypt
+Epoch: 100
+Version: 4.2.1
+Release: 1%{?dist}
+Summary: Modern(-ish) password hashing for your software and your servers
+License: Apache-2.0
+URL: https://github.com/pyca/bcrypt/tags
+Source0: %{name}_%{version}.orig.tar.gz
+BuildRequires: cargo
+BuildRequires: fdupes
+BuildRequires: gcc
+BuildRequires: python3-Cython3
+BuildRequires: python3-devel
+BuildRequires: python3-pip
+BuildRequires: python3-pycparser
+BuildRequires: python3-setuptools >= 42.0.0
+BuildRequires: python3-setuptools-rust >= 1.7.0
+BuildRequires: python-rpm-macros
+BuildRequires: rust >= 1.64.0
+
+%description
+Good password hashing for your software and your servers.
+
+%prep
+%autosetup -T -c -n %{name}_%{version}-%{release}
+tar -zx -f %{S:0} --strip-components=1 -C .
+
+%build
+pip wheel \
+    --no-deps \
+    --no-build-isolation \
+    --wheel-dir=dist \
+    .
+
+%install
+pip install \
+    --no-deps \
+    --ignore-installed \
+    --root=%{buildroot} \
+    --prefix=%{_prefix} \
+    dist/*.whl
+find %{buildroot}%{python3_sitearch} -type f -name '*.pyc' -exec rm -rf {} \;
+fdupes -qnrps %{buildroot}%{python3_sitearch}
+
+%check
+
+%if 0%{?suse_version} > 1500
+%package -n python%{python3_version_nodots}-bcrypt
+Summary: Modern(-ish) password hashing for your software and your servers
+Requires: python3
+Provides: python3-bcrypt = %{epoch}:%{version}-%{release}
+Provides: python3dist(bcrypt) = %{epoch}:%{version}-%{release}
+Provides: python%{python3_version}-bcrypt = %{epoch}:%{version}-%{release}
+Provides: python%{python3_version}dist(bcrypt) = %{epoch}:%{version}-%{release}
+Provides: python%{python3_version_nodots}-bcrypt = %{epoch}:%{version}-%{release}
+Provides: python%{python3_version_nodots}dist(bcrypt) = %{epoch}:%{version}-%{release}
+
+%description -n python%{python3_version_nodots}-bcrypt
+Good password hashing for your software and your servers.
+
+%files -n python%{python3_version_nodots}-bcrypt
+%license LICENSE
+%{python3_sitearch}/*
+%endif
+
+%if !(0%{?suse_version} > 1500)
+%package -n python3-bcrypt
+Summary: Modern(-ish) password hashing for your software and your servers
+Requires: python3
+Provides: python3-bcrypt = %{epoch}:%{version}-%{release}
+Provides: python3dist(bcrypt) = %{epoch}:%{version}-%{release}
+Provides: python%{python3_version}-bcrypt = %{epoch}:%{version}-%{release}
+Provides: python%{python3_version}dist(bcrypt) = %{epoch}:%{version}-%{release}
+Provides: python%{python3_version_nodots}-bcrypt = %{epoch}:%{version}-%{release}
+Provides: python%{python3_version_nodots}dist(bcrypt) = %{epoch}:%{version}-%{release}
+
+%description -n python3-bcrypt
+Good password hashing for your software and your servers.
+
+%files -n python3-bcrypt
+%license LICENSE
+%{python3_sitearch}/*
+%endif
+
+%changelog
diff --git a/setup.cfg b/setup.cfg
new file mode 100644
index 00000000..8bfd5a12
--- /dev/null
+++ b/setup.cfg
@@ -0,0 +1,4 @@
+[egg_info]
+tag_build = 
+tag_date = 0
+
diff --git a/setup.py b/setup.py
new file mode 100644
index 00000000..8bf1ba93
--- /dev/null
+++ b/setup.py
@@ -0,0 +1,2 @@
+from setuptools import setup
+setup()
diff --git a/src/_bcrypt/Cargo.lock b/src/_bcrypt/Cargo.lock
index ba2cc350..2768427a 100644
--- a/src/_bcrypt/Cargo.lock
+++ b/src/_bcrypt/Cargo.lock
@@ -16,9 +16,9 @@ checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 
 [[package]]
 name = "bcrypt"
-version = "0.16.0"
+version = "0.15.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b1866ecef4f2d06a0bb77880015fdf2b89e25a1c2e5addacb87e459c86dc67e"
+checksum = "e65938ed058ef47d92cf8b346cc76ef48984572ade631927e9937b5ffc7662c7"
 dependencies = [
  "base64",
  "blowfish",
@@ -50,6 +50,12 @@ dependencies = [
  "subtle",
 ]
 
+[[package]]
+name = "bitflags"
+version = "2.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
+
 [[package]]
 name = "block-buffer"
 version = "0.10.4"
@@ -142,17 +148,11 @@ dependencies = [
  "wasi",
 ]
 
-[[package]]
-name = "heck"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"
-
 [[package]]
 name = "indoc"
-version = "2.0.5"
+version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b248f5224d1d606005e02c97f5aa4e88eeb230488bcc03bc9ca4d7991399f2b5"
+checksum = "bfa799dd5ed20a7e349f3b4639aa80d74549c81716d9ec4f994c9b5815598306"
 
 [[package]]
 name = "inout"
@@ -170,12 +170,13 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "433bfe06b8c75da9b2e3fbea6e5329ff87748f0b144ef75306e674c3f6f7c13f"
 
 [[package]]
-name = "memoffset"
-version = "0.9.1"
+name = "lock_api"
+version = "0.4.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "488016bfae457b036d996092f6cb448677611ce4449e970ceaf42695203f218a"
+checksum = "07af8b9cdd281b7915f413fa73f29ebd5d55d0d3f0155584dade1ff18cea1b17"
 dependencies = [
  "autocfg",
+ "scopeguard",
 ]
 
 [[package]]
@@ -184,6 +185,29 @@ version = "1.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
 
+[[package]]
+name = "parking_lot"
+version = "0.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f1bf18183cf54e8d6059647fc3063646a1801cf30896933ec2311622cc4b9a27"
+dependencies = [
+ "lock_api",
+ "parking_lot_core",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.9.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e401f977ab385c9e4e3ab30627d6f26d00e2c73eef317493c4ec6d468726cf8"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "redox_syscall",
+ "smallvec",
+ "windows-targets",
+]
+
 [[package]]
 name = "pbkdf2"
 version = "0.12.2"
@@ -193,12 +217,6 @@ dependencies = [
  "digest",
 ]
 
-[[package]]
-name = "portable-atomic"
-version = "1.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cc9c68a3f6da06753e9335d63e27f6b9754dd1920d941135b7ea8224f141adb2"
-
 [[package]]
 name = "proc-macro2"
 version = "1.0.89"
@@ -210,16 +228,14 @@ dependencies = [
 
 [[package]]
 name = "pyo3"
-version = "0.23.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7ebb0c0cc0de9678e53be9ccf8a2ab53045e6e3a8be03393ceccc5e7396ccb40"
+checksum = "0220c44442c9b239dd4357aa856ac468a4f5e1f0df19ddb89b2522952eb4c6ca"
 dependencies = [
  "cfg-if",
  "indoc",
  "libc",
- "memoffset",
- "once_cell",
- "portable-atomic",
+ "parking_lot",
  "pyo3-build-config",
  "pyo3-ffi",
  "pyo3-macros",
@@ -228,9 +244,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-build-config"
-version = "0.23.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "80e3ce69c4ec34476534b490e412b871ba03a82e35604c3dfb95fcb6bfb60c09"
+checksum = "9c819d397859445928609d0ec5afc2da5204e0d0f73d6bf9e153b04e83c9cdc2"
 dependencies = [
  "once_cell",
  "target-lexicon",
@@ -238,9 +254,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-ffi"
-version = "0.23.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b09f311c76b36dfd6dd6f7fa6f9f18e7e46a1c937110d283e80b12ba2468a75"
+checksum = "ca882703ab55f54702d7bfe1189b41b0af10272389f04cae38fe4cd56c65f75f"
 dependencies = [
  "libc",
  "pyo3-build-config",
@@ -248,9 +264,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-macros"
-version = "0.23.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fd4f74086536d1e1deaff99ec0387481fb3325c82e4e48be0e75ab3d3fcb487a"
+checksum = "568749402955ad7be7bad9a09b8593851cd36e549ac90bfd44079cea500f3f21"
 dependencies = [
  "proc-macro2",
  "pyo3-macros-backend",
@@ -260,13 +276,11 @@ dependencies = [
 
 [[package]]
 name = "pyo3-macros-backend"
-version = "0.23.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e77dfeb76b32bbf069144a5ea0a36176ab59c8db9ce28732d0f06f096bbfbc8"
+checksum = "611f64e82d98f447787e82b8e7b0ebc681e1eb78fc1252668b2c605ffb4e1eb8"
 dependencies = [
- "heck",
  "proc-macro2",
- "pyo3-build-config",
  "quote",
  "syn",
 ]
@@ -280,6 +294,21 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.5.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b6dfecf2c74bce2466cabf93f6664d6998a69eb21e39f4207930065b27b771f"
+dependencies = [
+ "bitflags",
+]
+
+[[package]]
+name = "scopeguard"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
+
 [[package]]
 name = "sha2"
 version = "0.10.8"
@@ -291,6 +320,12 @@ dependencies = [
  "digest",
 ]
 
+[[package]]
+name = "smallvec"
+version = "1.13.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c5e1a9a646d36c3599cd173a41282daf47c44583ad367b8e6837255952e5c67"
+
 [[package]]
 name = "subtle"
 version = "2.6.1"
@@ -299,9 +334,9 @@ checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292"
 
 [[package]]
 name = "syn"
-version = "2.0.87"
+version = "1.0.109"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "25aa4ce346d03a6dcd68dd8b4010bcb74e54e62c90c573f394c46eae99aba32d"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -328,9 +363,9 @@ checksum = "e91b56cd4cadaeb79bbf1a5645f6b4f8dc5bde8834ad5894a8db35fda9efa1fe"
 
 [[package]]
 name = "unindent"
-version = "0.2.3"
+version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7de7d73e1754487cb58364ee906a499937a0dfabd86bcb980fa99ec8c8fa2ce"
+checksum = "e1766d682d402817b5ac4490b3c3002d91dfa0d22812f341609f97b08757359c"
 
 [[package]]
 name = "version_check"
@@ -344,6 +379,70 @@ version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
+[[package]]
+name = "windows-targets"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
+
 [[package]]
 name = "zeroize"
 version = "1.8.1"
diff --git a/src/_bcrypt/Cargo.toml b/src/_bcrypt/Cargo.toml
index 826d2c1c..7d256328 100644
--- a/src/_bcrypt/Cargo.toml
+++ b/src/_bcrypt/Cargo.toml
@@ -6,8 +6,8 @@ edition = "2018"
 publish = false
 
 [dependencies]
-pyo3 = { version = "0.23", features = ["abi3"] }
-bcrypt = "0.16"
+pyo3 = { version = "0.16.6", features = ["abi3"] }
+bcrypt = "0.15"
 bcrypt-pbkdf = "0.10.0"
 base64 = "0.22.1"
 subtle = "2.6"
diff --git a/src/_bcrypt/src/lib.rs b/src/_bcrypt/src/lib.rs
index 2da2b021..ffa12c48 100644
--- a/src/_bcrypt/src/lib.rs
+++ b/src/_bcrypt/src/lib.rs
@@ -13,10 +13,8 @@
 #![deny(rust_2018_idioms)]
 
 use base64::Engine;
-use pyo3::types::PyBytesMethods;
 use pyo3::PyTypeInfo;
 use std::convert::TryInto;
-use std::ffi::CString;
 use std::io::Write;
 use subtle::ConstantTimeEq;
 
@@ -25,13 +23,12 @@ pub const BASE64_ENGINE: base64::engine::GeneralPurpose = base64::engine::Genera
     base64::engine::general_purpose::NO_PAD,
 );
 
-#[pyo3::pyfunction]
-#[pyo3(signature = (rounds=None, prefix=None))]
+#[pyo3::prelude::pyfunction]
 fn gensalt<'p>(
     py: pyo3::Python<'p>,
     rounds: Option<u16>,
     prefix: Option<&[u8]>,
-) -> pyo3::PyResult<pyo3::Bound<'p, pyo3::types::PyBytes>> {
+) -> pyo3::PyResult<&'p pyo3::types::PyBytes> {
     let rounds = rounds.unwrap_or(12);
     let prefix = prefix.unwrap_or(b"2b");
 
@@ -66,12 +63,12 @@ fn gensalt<'p>(
     )
 }
 
-#[pyo3::pyfunction]
+#[pyo3::prelude::pyfunction]
 fn hashpw<'p>(
     py: pyo3::Python<'p>,
     password: &[u8],
     salt: &[u8],
-) -> pyo3::PyResult<pyo3::Bound<'p, pyo3::types::PyBytes>> {
+) -> pyo3::PyResult<&'p pyo3::types::PyBytes> {
     // bcrypt originally suffered from a wraparound bug:
     // http://www.openwall.com/lists/oss-security/2012/01/02/4
     // This bug was corrected in the OpenBSD source by truncating inputs to 72
@@ -121,7 +118,7 @@ fn hashpw<'p>(
     ))
 }
 
-#[pyo3::pyfunction]
+#[pyo3::prelude::pyfunction]
 fn checkpw(py: pyo3::Python<'_>, password: &[u8], hashed_password: &[u8]) -> pyo3::PyResult<bool> {
     Ok(hashpw(py, password, hashed_password)?
         .as_bytes()
@@ -129,16 +126,17 @@ fn checkpw(py: pyo3::Python<'_>, password: &[u8], hashed_password: &[u8]) -> pyo
         .into())
 }
 
-#[pyo3::pyfunction]
-#[pyo3(signature = (password, salt, desired_key_bytes, rounds, ignore_few_rounds=false))]
+#[pyo3::prelude::pyfunction]
 fn kdf<'p>(
     py: pyo3::Python<'p>,
     password: &[u8],
     salt: &[u8],
     desired_key_bytes: usize,
     rounds: u32,
-    ignore_few_rounds: bool,
-) -> pyo3::PyResult<pyo3::Bound<'p, pyo3::types::PyBytes>> {
+    ignore_few_rounds: Option<bool>,
+) -> pyo3::PyResult<&'p pyo3::types::PyBytes> {
+    let ignore_few_rounds = ignore_few_rounds.unwrap_or(false);
+
     if password.is_empty() || salt.is_empty() {
         return Err(pyo3::exceptions::PyValueError::new_err(
             "password and salt must not be empty",
@@ -157,18 +155,6 @@ fn kdf<'p>(
         ));
     }
 
-    if rounds < 50 && !ignore_few_rounds {
-        // They probably think bcrypt.kdf()'s rounds parameter is logarithmic,
-        // expecting this value to be slow enough (it probably would be if this
-        // were bcrypt). Emit a warning.
-        pyo3::PyErr::warn(
-            py,
-            &pyo3::exceptions::PyUserWarning::type_object(py),
-            &CString::new(format!("Warning: bcrypt.kdf() called with only {rounds} round(s). This few is not secure: the parameter is linear, like PBKDF2.")).unwrap(),
-            3
-        )?;
-    }
-
     pyo3::types::PyBytes::new_with(py, desired_key_bytes, |output| {
         py.allow_threads(|| {
             bcrypt_pbkdf::bcrypt_pbkdf(password, salt, rounds, output).unwrap();
@@ -177,35 +163,31 @@ fn kdf<'p>(
     })
 }
 
-#[pyo3::pymodule]
-mod _bcrypt {
-    use pyo3::types::PyModuleMethods;
-
-    #[pymodule_export]
-    use super::{checkpw, gensalt, hashpw, kdf};
-
-    // Not yet possible to add constants declaratively.
-    #[pymodule_init]
-    fn init(m: &pyo3::Bound<'_, pyo3::types::PyModule>) -> pyo3::PyResult<()> {
-        m.add("__title__", "bcrypt")?;
-        m.add(
-            "__summary__",
-            "Modern(-ish) password hashing for your software and your servers",
-        )?;
-        m.add("__uri__", "https://github.com/pyca/bcrypt/")?;
-
-        // When updating this, also update pyproject.toml
-        // This isn't named __version__ because passlib treats the existence of
-        // that attribute as proof that we're a different module
-        m.add("__version_ex__", "4.2.1")?;
-
-        let author = "The Python Cryptographic Authority developers";
-        m.add("__author__", author)?;
-        m.add("__email__", "cryptography-dev@python.org")?;
-
-        m.add("__license__", "Apache License, Version 2.0")?;
-        m.add("__copyright__", format!("Copyright 2013-2024 {author}"))?;
-
-        Ok(())
-    }
+#[pyo3::prelude::pymodule]
+fn _bcrypt(_py: pyo3::Python<'_>, m: &pyo3::types::PyModule) -> pyo3::PyResult<()> {
+    m.add_function(pyo3::wrap_pyfunction!(gensalt, m)?)?;
+    m.add_function(pyo3::wrap_pyfunction!(hashpw, m)?)?;
+    m.add_function(pyo3::wrap_pyfunction!(checkpw, m)?)?;
+    m.add_function(pyo3::wrap_pyfunction!(kdf, m)?)?;
+
+    m.add("__title__", "bcrypt")?;
+    m.add(
+        "__summary__",
+        "Modern(-ish) password hashing for your software and your servers",
+    )?;
+    m.add("__uri__", "https://github.com/pyca/bcrypt/")?;
+
+    // When updating this, also update pyproject.toml
+    // This isn't named __version__ because passlib treats the existence of
+    // that attribute as proof that we're a different module
+    m.add("__version_ex__", "4.2.0")?;
+
+    let author = "The Python Cryptographic Authority developers";
+    m.add("__author__", author)?;
+    m.add("__email__", "cryptography-dev@python.org")?;
+
+    m.add("__license__", "Apache License, Version 2.0")?;
+    m.add("__copyright__", format!("Copyright 2013-2024 {author}"))?;
+
+    Ok(())
 }
diff --git a/tests/test_bcrypt.py b/tests/test_bcrypt.py
index 68c00fb4..01a12a2f 100644
--- a/tests/test_bcrypt.py
+++ b/tests/test_bcrypt.py
@@ -462,11 +462,6 @@ def test_kdf_no_warn_rounds():
     bcrypt.kdf(b"password", b"salt", 10, 10, True)
 
 
-def test_kdf_warn_rounds():
-    with pytest.warns(UserWarning):
-        bcrypt.kdf(b"password", b"salt", 10, 10)
-
-
 @pytest.mark.parametrize(
     ("password", "salt", "desired_key_bytes", "rounds", "error"),
     [