diff --git a/src/_bcrypt/Cargo.lock b/src/_bcrypt/Cargo.lock
index 9353ee9e..729bcc0a 100644
--- a/src/_bcrypt/Cargo.lock
+++ b/src/_bcrypt/Cargo.lock
@@ -148,17 +148,11 @@ dependencies = [
  "wasi",
 ]
 
-[[package]]
-name = "heck"
-version = "0.4.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"
-
 [[package]]
 name = "indoc"
-version = "2.0.4"
+version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e186cfbae8084e513daff4240b4797e342f988cecda4fb6c939150f96315fd8"
+checksum = "bfa799dd5ed20a7e349f3b4639aa80d74549c81716d9ec4f994c9b5815598306"
 
 [[package]]
 name = "inout"
@@ -185,15 +179,6 @@ dependencies = [
  "scopeguard",
 ]
 
-[[package]]
-name = "memoffset"
-version = "0.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a634b1c61a95585bd15607c6ab0c4e5b226e695ff2800ba0cdccddf208c406c"
-dependencies = [
- "autocfg",
-]
-
 [[package]]
 name = "once_cell"
 version = "1.19.0"
@@ -243,14 +228,13 @@ dependencies = [
 
 [[package]]
 name = "pyo3"
-version = "0.20.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e82ad98ce1991c9c70c3464ba4187337b9c45fcbbb060d46dca15f0c075e14e2"
+checksum = "0220c44442c9b239dd4357aa856ac468a4f5e1f0df19ddb89b2522952eb4c6ca"
 dependencies = [
  "cfg-if",
  "indoc",
  "libc",
- "memoffset",
  "parking_lot",
  "pyo3-build-config",
  "pyo3-ffi",
@@ -260,9 +244,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-build-config"
-version = "0.20.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5503d0b3aee2c7a8dbb389cd87cd9649f675d4c7f60ca33699a3e3859d81a891"
+checksum = "9c819d397859445928609d0ec5afc2da5204e0d0f73d6bf9e153b04e83c9cdc2"
 dependencies = [
  "once_cell",
  "target-lexicon",
@@ -270,9 +254,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-ffi"
-version = "0.20.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "18a79e8d80486a00d11c0dcb27cd2aa17c022cc95c677b461f01797226ba8f41"
+checksum = "ca882703ab55f54702d7bfe1189b41b0af10272389f04cae38fe4cd56c65f75f"
 dependencies = [
  "libc",
  "pyo3-build-config",
@@ -280,9 +264,9 @@ dependencies = [
 
 [[package]]
 name = "pyo3-macros"
-version = "0.20.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1f4b0dc7eaa578604fab11c8c7ff8934c71249c61d4def8e272c76ed879f03d4"
+checksum = "568749402955ad7be7bad9a09b8593851cd36e549ac90bfd44079cea500f3f21"
 dependencies = [
  "proc-macro2",
  "pyo3-macros-backend",
@@ -292,11 +276,10 @@ dependencies = [
 
 [[package]]
 name = "pyo3-macros-backend"
-version = "0.20.1"
+version = "0.16.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "816a4f709e29ddab2e3cdfe94600d554c5556cad0ddfeea95c47b580c3247fa4"
+checksum = "611f64e82d98f447787e82b8e7b0ebc681e1eb78fc1252668b2c605ffb4e1eb8"
 dependencies = [
- "heck",
  "proc-macro2",
  "quote",
  "syn",
@@ -351,9 +334,9 @@ checksum = "81cdd64d312baedb58e21336b31bc043b77e01cc99033ce76ef539f78e965ebc"
 
 [[package]]
 name = "syn"
-version = "2.0.45"
+version = "1.0.109"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0eae3c679c56dc214320b67a1bc04ef3dfbd6411f6443974b5e4893231298e66"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -380,9 +363,9 @@ checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
 
 [[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"
diff --git a/src/_bcrypt/Cargo.toml b/src/_bcrypt/Cargo.toml
index 40082740..36dc219f 100644
--- a/src/_bcrypt/Cargo.toml
+++ b/src/_bcrypt/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2018"
 publish = false
 
 [dependencies]
-pyo3 = { version = "0.20.1", features = ["abi3"] }
+pyo3 = { version = "0.16.6", features = ["abi3"] }
 bcrypt = "0.15"
 bcrypt-pbkdf = "0.10.0"
 base64 = "0.21.5"
diff --git a/src/_bcrypt/src/lib.rs b/src/_bcrypt/src/lib.rs
index a3472148..72405aae 100644
--- a/src/_bcrypt/src/lib.rs
+++ b/src/_bcrypt/src/lib.rs
@@ -151,18 +151,6 @@ 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),
-            &format!("Warning: bcrypt.kdf() called with only {rounds} round(s). This few is not secure: the parameter is linear, like PBKDF2."),
-            3
-        )?;
-    }
-
     pyo3::types::PyBytes::new_with(py, desired_key_bytes, |output| {
         py.allow_threads(|| {
             bcrypt_pbkdf::bcrypt_pbkdf(password, salt, rounds, output).unwrap();
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"),
     [