diff --git a/native/Cargo.lock b/native/Cargo.lock
index bd1424b9..036512c0 100644
--- a/native/Cargo.lock
+++ b/native/Cargo.lock
@@ -718,9 +718,9 @@ dependencies = [
 
 [[package]]
 name = "fastcdc"
-version = "3.2.1"
+version = "4.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bf51ceb43e96afbfe4dd5c6f6082af5dfd60e220820b8123792d61963f2ce6bc"
+checksum = "77af40d8a8dadb92dc178569a5f5edb5f3056e98255c2de48ab5d59a52892e0c"
 
 [[package]]
 name = "fastrand"
diff --git a/native/Cargo.toml b/native/Cargo.toml
index 1f5d4c65..90115d4a 100644
--- a/native/Cargo.toml
+++ b/native/Cargo.toml
@@ -92,7 +92,7 @@ memchr       = "2.7"
 # cryptographic collision resistance.
 xxhash-rust  = { version = "0.8", features = ["xxh3"] }
 # Content-defined chunking (FastCDC/Gear-256 per ADR-0001).
-fastcdc      = "3.1"
+fastcdc      = "4.0"
 # AEAD primitives. RustCrypto suite is the standard well-audited choice;
 # AES-256-GCM uses aesni hardware accel on x86 (AVX2 + AES-NI), NEON on ARM.
 # ChaCha20-Poly1305 fallback runs on every architecture in constant time.