diff --git a/Cargo.lock b/Cargo.lock
index dcfd0f61d..40fc9933d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -280,7 +280,7 @@ dependencies = [
  "lru-cache 0.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
- "rayon 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rayon 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rust-crypto 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "semver 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1193,7 +1193,7 @@ dependencies = [
 
 [[package]]
 name = "rayon"
-version = "0.3.1"
+version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "deque 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/ethcore/Cargo.toml b/ethcore/Cargo.toml
index ca2aca5f8..1c9d41094 100644
--- a/ethcore/Cargo.toml
+++ b/ethcore/Cargo.toml
@@ -20,7 +20,7 @@ num_cpus = "0.2"
 crossbeam = "0.2.9"
 lazy_static = "0.2"
 bloomchain = "0.1"
-rayon = "0.3.1"
+rayon = "0.4"
 semver = "0.2"
 bit-set = "0.4"
 time = "0.1"