diff --git a/README.md b/README.md
index 1a287bdac..0f0d7a526 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,15 @@
+# Unsafe Fast Fork
+## DO NOT USE THIS LIBRARY
+
+This is an experimental fork with extreme changes that **intentionally break important security mechanisms and functionality** in favor of speed for certain security research workloads.
+
+The forked library version is **completely unsuitable for any type of production use** and receives no support or maintenance of any kind.
+It is published primarily as a reference for other researchers. You have been warned.
+
+The original documentation content and other references are kept as-is to limit the repository differences to upstream. However, be aware that none of the contact information, usage guidance or security guarantees still applies since this is a deliberately broken variant of the project.
+
+----
+
 <div align="center">
   <h1>Rust Bitcoin</h1>
 
diff --git a/bitcoin/Cargo.toml b/bitcoin/Cargo.toml
index 2e3ff37a6..a555e35f9 100644
--- a/bitcoin/Cargo.toml
+++ b/bitcoin/Cargo.toml
@@ -1,6 +1,7 @@
 [package]
 name = "bitcoin"
-version = "0.33.0-alpha.0"
+# fake version for vendoring
+version = "0.99.0"
 authors = ["Andrew Poelstra <apoelstra@wpsoftware.net>"]
 license = "CC0-1.0"
 repository = "https://github.com/rust-bitcoin/rust-bitcoin/"
@@ -33,7 +34,7 @@ hex = { package = "hex-conservative", version = "0.3.0", default-features = fals
 internals = { package = "bitcoin-internals", path = "../internals", features = ["alloc", "hex"] }
 io = { package = "bitcoin-io", path = "../io", default-features = false, features = ["alloc", "hashes"] }
 primitives = { package = "bitcoin-primitives", path = "../primitives", default-features = false, features = ["alloc", "hex"] }
-secp256k1 = { version = "0.30.0", default-features = false, features = ["hashes", "alloc", "rand"] }
+secp256k1 = { version = "0.99.0", default-features = false, features = ["hashes", "alloc", "rand"] } # ensure the internal version is actually used
 units = { package = "bitcoin-units", path = "../units", default-features = false, features = ["alloc"] }
 
 arbitrary = { version = "1.4", optional = true }
diff --git a/bitcoin/src/bip32.rs b/bitcoin/src/bip32.rs
index 847335b4f..46ed7922d 100644
--- a/bitcoin/src/bip32.rs
+++ b/bitcoin/src/bip32.rs
@@ -805,10 +805,14 @@ impl Xpriv {
         let tweaked =
             sk.add_tweak(&self.private_key.into()).expect("statistically impossible to hit");
 
+        // BREAKING CHANGE
+        // parent_fingerprint: self.fingerprint(secp),
+        // this brings a strong performance improvement
+        // TODO check performance impact of error handling
         Ok(Xpriv {
             network: self.network,
             depth: self.depth.checked_add(1).ok_or(DerivationError::MaximumDepthExceeded)?,
-            parent_fingerprint: self.fingerprint(secp),
+            parent_fingerprint: Default::default(),
             child_number: i,
             private_key: tweaked,
             chain_code: ChainCode::from_hmac(hmac),
@@ -963,10 +967,14 @@ impl Xpub {
         let tweaked =
             self.public_key.add_exp_tweak(secp, &sk.into()).expect("cryptographically unreachable");
 
+        // BREAKING CHANGE
+        // parent_fingerprint: self.fingerprint(),
+        // this brings less of a performance improvement
+        // TODO check performance impact of error handling
         Ok(Xpub {
             network: self.network,
             depth: self.depth.checked_add(1).ok_or(DerivationError::MaximumDepthExceeded)?,
-            parent_fingerprint: self.fingerprint(),
+            parent_fingerprint: Default::default(),
             child_number: i,
             public_key: tweaked,
             chain_code,