diff --git a/Cargo.lock b/Cargo.lock
index db33c59f803c..3128ca67537d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -900,7 +900,7 @@ dependencies = [
  "parity-scale-codec",
  "polkadot-parachain-primitives",
  "polkadot-runtime-common",
- "primitive-types",
+ "primitive-types 0.13.1",
  "rococo-runtime-constants",
  "scale-info",
  "serde_json",
@@ -1033,7 +1033,7 @@ dependencies = [
  "parity-scale-codec",
  "polkadot-parachain-primitives",
  "polkadot-runtime-common",
- "primitive-types",
+ "primitive-types 0.13.1",
  "scale-info",
  "serde_json",
  "snowbridge-router-primitives",
@@ -5755,11 +5755,11 @@ dependencies = [
 
 [[package]]
 name = "ethabi-decode"
-version = "1.0.0"
+version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "09d398648d65820a727d6a81e58b962f874473396a047e4c30bafe3240953417"
+checksum = "f9af52ec57c5147716872863c2567c886e7d62f539465b94352dbc0108fe5293"
 dependencies = [
- "ethereum-types",
+ "ethereum-types 0.15.1",
  "tiny-keccak",
 ]
 
@@ -5771,9 +5771,22 @@ checksum = "c22d4b5885b6aa2fe5e8b9329fb8d232bf739e434e6b87347c63bdd00c120f60"
 dependencies = [
  "crunchy",
  "fixed-hash",
- "impl-codec",
- "impl-rlp",
- "impl-serde",
+ "impl-rlp 0.3.0",
+ "impl-serde 0.4.0",
+ "tiny-keccak",
+]
+
+[[package]]
+name = "ethbloom"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8c321610643004cf908ec0f5f2aa0d8f1f8e14b540562a2887a1111ff1ecbf7b"
+dependencies = [
+ "crunchy",
+ "fixed-hash",
+ "impl-codec 0.7.0",
+ "impl-rlp 0.4.0",
+ "impl-serde 0.5.0",
  "scale-info",
  "tiny-keccak",
 ]
@@ -5784,14 +5797,28 @@ version = "0.14.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "02d215cbf040552efcbe99a38372fe80ab9d00268e20012b79fcd0f073edd8ee"
 dependencies = [
- "ethbloom",
+ "ethbloom 0.13.0",
+ "fixed-hash",
+ "impl-rlp 0.3.0",
+ "impl-serde 0.4.0",
+ "primitive-types 0.12.2",
+ "uint 0.9.5",
+]
+
+[[package]]
+name = "ethereum-types"
+version = "0.15.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ab15ed80916029f878e0267c3a9f92b67df55e79af370bf66199059ae2b4ee3"
+dependencies = [
+ "ethbloom 0.14.1",
  "fixed-hash",
- "impl-codec",
- "impl-rlp",
- "impl-serde",
- "primitive-types",
+ "impl-codec 0.7.0",
+ "impl-rlp 0.4.0",
+ "impl-serde 0.5.0",
+ "primitive-types 0.13.1",
  "scale-info",
- "uint",
+ "uint 0.10.0",
 ]
 
 [[package]]
@@ -7609,6 +7636,15 @@ dependencies = [
  "parity-scale-codec",
 ]
 
+[[package]]
+name = "impl-codec"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b67aa010c1e3da95bf151bd8b4c059b2ed7e75387cdb969b4f8f2723a43f9941"
+dependencies = [
+ "parity-scale-codec",
+]
+
 [[package]]
 name = "impl-num-traits"
 version = "0.1.2"
@@ -7617,7 +7653,18 @@ checksum = "951641f13f873bff03d4bf19ae8bec531935ac0ac2cc775f84d7edfdcfed3f17"
 dependencies = [
  "integer-sqrt",
  "num-traits",
- "uint",
+ "uint 0.9.5",
+]
+
+[[package]]
+name = "impl-num-traits"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "803d15461ab0dcc56706adf266158acbc44ccf719bf7d0af30705f58b90a4b8c"
+dependencies = [
+ "integer-sqrt",
+ "num-traits",
+ "uint 0.10.0",
 ]
 
 [[package]]
@@ -7626,7 +7673,16 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f28220f89297a075ddc7245cd538076ee98b01f2a9c23a53a4f1105d5a322808"
 dependencies = [
- "rlp",
+ "rlp 0.5.2",
+]
+
+[[package]]
+name = "impl-rlp"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "54ed8ad1f3877f7e775b8cbf30ed1bd3209a95401817f19a0eb4402d13f8cf90"
+dependencies = [
+ "rlp 0.6.1",
 ]
 
 [[package]]
@@ -7638,6 +7694,15 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "impl-serde"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4a143eada6a1ec4aefa5049037a26a6d597bfd64f8c026d07b77133e02b7dd0b"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "impl-trait-for-tuples"
 version = "0.2.2"
@@ -8371,7 +8436,7 @@ dependencies = [
  "pallet-example-tasks",
  "parity-scale-codec",
  "polkadot-sdk",
- "primitive-types",
+ "primitive-types 0.13.1",
  "scale-info",
  "serde_json",
  "static_assertions",
@@ -8784,7 +8849,7 @@ dependencies = [
  "sha2 0.10.8",
  "smallvec",
  "thiserror",
- "uint",
+ "uint 0.9.5",
  "unsigned-varint 0.7.2",
  "void",
 ]
@@ -9247,7 +9312,7 @@ dependencies = [
  "tokio-tungstenite",
  "tokio-util",
  "tracing",
- "uint",
+ "uint 0.9.5",
  "unsigned-varint 0.8.0",
  "url",
  "x25519-dalek",
@@ -10651,7 +10716,7 @@ dependencies = [
  "pallet-assets",
  "pallet-balances",
  "parity-scale-codec",
- "primitive-types",
+ "primitive-types 0.13.1",
  "scale-info",
  "sp-api 26.0.0",
  "sp-arithmetic 23.0.0",
@@ -10672,7 +10737,7 @@ dependencies = [
  "pallet-assets",
  "pallet-balances",
  "parity-scale-codec",
- "primitive-types",
+ "primitive-types 0.13.1",
  "scale-info",
  "sp-arithmetic 23.0.0",
  "sp-core 28.0.0",
@@ -12335,7 +12400,7 @@ dependencies = [
  "paste",
  "polkavm 0.11.0",
  "pretty_assertions",
- "rlp",
+ "rlp 0.6.1",
  "scale-info",
  "serde",
  "sp-api 26.0.0",
@@ -13244,7 +13309,7 @@ checksum = "4e69bf016dc406eff7d53a7d3f7cf1c2e72c82b9088aac1118591e36dd2cd3e9"
 dependencies = [
  "bitcoin_hashes 0.13.0",
  "rand",
- "rand_core 0.6.4",
+ "rand_core 0.5.1",
  "serde",
  "unicode-normalization",
 ]
@@ -13309,13 +13374,13 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0d32c34f4f5ca7f9196001c0aba5a1f9a5a12382c8944b8b0f90233282d1e8f8"
 dependencies = [
  "cfg-if",
- "ethereum-types",
+ "ethereum-types 0.14.1",
  "hashbrown 0.12.3",
  "impl-trait-for-tuples",
  "lru 0.8.1",
  "parity-util-mem-derive",
  "parking_lot 0.12.3",
- "primitive-types",
+ "primitive-types 0.12.2",
  "smallvec",
  "winapi",
 ]
@@ -13502,7 +13567,7 @@ dependencies = [
  "polkadot-parachain-primitives",
  "polkadot-primitives",
  "polkadot-runtime-common",
- "primitive-types",
+ "primitive-types 0.12.2",
  "scale-info",
  "smallvec",
  "sp-api 26.0.0",
@@ -16562,12 +16627,27 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b34d9fd68ae0b74a41b21c03c2f62847aa0ffea044eee893b4c140b37e244e2"
 dependencies = [
  "fixed-hash",
- "impl-codec",
- "impl-num-traits",
- "impl-rlp",
- "impl-serde",
+ "impl-codec 0.6.0",
+ "impl-num-traits 0.1.2",
+ "impl-rlp 0.3.0",
+ "impl-serde 0.4.0",
+ "scale-info",
+ "uint 0.9.5",
+]
+
+[[package]]
+name = "primitive-types"
+version = "0.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d15600a7d856470b7d278b3fe0e311fe28c2526348549f8ef2ff7db3299c87f5"
+dependencies = [
+ "fixed-hash",
+ "impl-codec 0.7.0",
+ "impl-num-traits 0.2.0",
+ "impl-rlp 0.4.0",
+ "impl-serde 0.5.0",
  "scale-info",
- "uint",
+ "uint 0.10.0",
 ]
 
 [[package]]
@@ -17679,6 +17759,16 @@ dependencies = [
  "rustc-hex",
 ]
 
+[[package]]
+name = "rlp"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fa24e92bb2a83198bb76d661a71df9f7076b8c420b8696e4d3d97d50d94479e3"
+dependencies = [
+ "bytes",
+ "rustc-hex",
+]
+
 [[package]]
 name = "rocksdb"
 version = "0.21.0"
@@ -17989,10 +18079,10 @@ dependencies = [
  "num-bigint",
  "num-traits",
  "parity-scale-codec",
- "primitive-types",
+ "primitive-types 0.12.2",
  "proptest",
  "rand",
- "rlp",
+ "rlp 0.5.2",
  "ruint-macro",
  "serde",
  "valuable",
@@ -19922,7 +20012,7 @@ checksum = "e98f3262c250d90e700bb802eb704e1f841e03331c2eb815e46516c4edbf5b27"
 dependencies = [
  "derive_more",
  "parity-scale-codec",
- "primitive-types",
+ "primitive-types 0.12.2",
  "scale-bits",
  "scale-decode-derive",
  "scale-type-resolver",
@@ -19949,7 +20039,7 @@ checksum = "4ba0b9c48dc0eb20c60b083c29447c0c4617cb7c4a4c9fef72aa5c5bc539e15e"
 dependencies = [
  "derive_more",
  "parity-scale-codec",
- "primitive-types",
+ "primitive-types 0.12.2",
  "scale-bits",
  "scale-encode-derive",
  "scale-type-resolver",
@@ -20981,7 +21071,7 @@ dependencies = [
  "hex",
  "hex-literal",
  "parity-scale-codec",
- "rlp",
+ "rlp 0.6.1",
  "scale-info",
  "serde",
  "snowbridge-ethereum",
@@ -21023,13 +21113,13 @@ name = "snowbridge-ethereum"
 version = "0.3.0"
 dependencies = [
  "ethabi-decode",
- "ethbloom",
- "ethereum-types",
+ "ethbloom 0.14.1",
+ "ethereum-types 0.15.1",
  "hex-literal",
  "parity-bytes",
  "parity-scale-codec",
  "rand",
- "rlp",
+ "rlp 0.6.1",
  "scale-info",
  "serde",
  "serde-big-array",
@@ -21584,7 +21674,7 @@ dependencies = [
  "integer-sqrt",
  "num-traits",
  "parity-scale-codec",
- "primitive-types",
+ "primitive-types 0.13.1",
  "rand",
  "scale-info",
  "serde",
@@ -21824,7 +21914,7 @@ dependencies = [
  "futures",
  "hash-db",
  "hash256-std-hasher",
- "impl-serde",
+ "impl-serde 0.4.0",
  "itertools 0.11.0",
  "k256",
  "libsecp256k1",
@@ -21834,7 +21924,7 @@ dependencies = [
  "parity-scale-codec",
  "parking_lot 0.12.3",
  "paste",
- "primitive-types",
+ "primitive-types 0.13.1",
  "rand",
  "regex",
  "scale-info",
@@ -21873,7 +21963,7 @@ dependencies = [
  "futures",
  "hash-db",
  "hash256-std-hasher",
- "impl-serde",
+ "impl-serde 0.4.0",
  "itertools 0.10.5",
  "k256",
  "libsecp256k1",
@@ -21883,7 +21973,7 @@ dependencies = [
  "parity-scale-codec",
  "parking_lot 0.12.3",
  "paste",
- "primitive-types",
+ "primitive-types 0.12.2",
  "rand",
  "scale-info",
  "schnorrkel 0.11.4",
@@ -21920,7 +22010,7 @@ dependencies = [
  "futures",
  "hash-db",
  "hash256-std-hasher",
- "impl-serde",
+ "impl-serde 0.4.0",
  "itertools 0.10.5",
  "k256",
  "libsecp256k1",
@@ -21930,7 +22020,7 @@ dependencies = [
  "parity-scale-codec",
  "parking_lot 0.12.3",
  "paste",
- "primitive-types",
+ "primitive-types 0.12.2",
  "rand",
  "scale-info",
  "schnorrkel 0.11.4",
@@ -21967,7 +22057,7 @@ dependencies = [
  "futures",
  "hash-db",
  "hash256-std-hasher",
- "impl-serde",
+ "impl-serde 0.4.0",
  "itertools 0.11.0",
  "k256",
  "libsecp256k1",
@@ -21977,7 +22067,7 @@ dependencies = [
  "parity-scale-codec",
  "parking_lot 0.12.3",
  "paste",
- "primitive-types",
+ "primitive-types 0.12.2",
  "rand",
  "scale-info",
  "schnorrkel 0.11.4",
@@ -22622,7 +22712,7 @@ dependencies = [
  "bytes",
  "impl-trait-for-tuples",
  "parity-scale-codec",
- "primitive-types",
+ "primitive-types 0.12.2",
  "sp-externalities 0.19.0",
  "sp-runtime-interface-proc-macro 11.0.0",
  "sp-std 8.0.0",
@@ -22640,7 +22730,7 @@ dependencies = [
  "impl-trait-for-tuples",
  "parity-scale-codec",
  "polkavm-derive 0.9.1",
- "primitive-types",
+ "primitive-types 0.13.1",
  "rustversion",
  "sp-core 28.0.0",
  "sp-externalities 0.25.0",
@@ -22666,7 +22756,7 @@ dependencies = [
  "impl-trait-for-tuples",
  "parity-scale-codec",
  "polkavm-derive 0.8.0",
- "primitive-types",
+ "primitive-types 0.12.2",
  "sp-externalities 0.27.0",
  "sp-runtime-interface-proc-macro 18.0.0",
  "sp-std 14.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -22686,7 +22776,7 @@ dependencies = [
  "impl-trait-for-tuples",
  "parity-scale-codec",
  "polkavm-derive 0.9.1",
- "primitive-types",
+ "primitive-types 0.12.2",
  "sp-externalities 0.28.0",
  "sp-runtime-interface-proc-macro 18.0.0",
  "sp-std 14.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -22927,7 +23017,7 @@ name = "sp-storage"
 version = "13.0.0"
 source = "git+https://github.com/paritytech/polkadot-sdk#82912acb33a9030c0ef3bf590a34fca09b72dc5f"
 dependencies = [
- "impl-serde",
+ "impl-serde 0.4.0",
  "parity-scale-codec",
  "ref-cast",
  "serde",
@@ -22939,7 +23029,7 @@ dependencies = [
 name = "sp-storage"
 version = "19.0.0"
 dependencies = [
- "impl-serde",
+ "impl-serde 0.4.0",
  "parity-scale-codec",
  "ref-cast",
  "serde",
@@ -22952,7 +23042,7 @@ version = "20.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8dba5791cb3978e95daf99dad919ecb3ec35565604e88cd38d805d9d4981e8bd"
 dependencies = [
- "impl-serde",
+ "impl-serde 0.4.0",
  "parity-scale-codec",
  "ref-cast",
  "serde",
@@ -22966,7 +23056,7 @@ version = "21.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "99c82989b3a4979a7e1ad848aad9f5d0b4388f1f454cc131766526601ab9e8f8"
 dependencies = [
- "impl-serde",
+ "impl-serde 0.4.0",
  "parity-scale-codec",
  "ref-cast",
  "serde",
@@ -23167,7 +23257,7 @@ dependencies = [
 name = "sp-version"
 version = "29.0.0"
 dependencies = [
- "impl-serde",
+ "impl-serde 0.4.0",
  "parity-scale-codec",
  "parity-wasm",
  "scale-info",
@@ -23185,7 +23275,7 @@ version = "35.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6ff74bf12b4f7d29387eb1caeec5553209a505f90a2511d2831143b970f89659"
 dependencies = [
- "impl-serde",
+ "impl-serde 0.4.0",
  "parity-scale-codec",
  "parity-wasm",
  "scale-info",
@@ -23519,7 +23609,7 @@ dependencies = [
  "polkadot-primitives",
  "polkadot-runtime-parachains",
  "polkadot-test-runtime",
- "primitive-types",
+ "primitive-types 0.13.1",
  "scale-info",
  "sp-arithmetic 23.0.0",
  "sp-core 28.0.0",
@@ -24145,11 +24235,11 @@ dependencies = [
  "frame-metadata 16.0.0",
  "futures",
  "hex",
- "impl-serde",
+ "impl-serde 0.4.0",
  "instant",
  "jsonrpsee 0.22.5",
  "parity-scale-codec",
- "primitive-types",
+ "primitive-types 0.12.2",
  "reconnecting-jsonrpsee-ws-client",
  "scale-bits",
  "scale-decode",
@@ -24202,9 +24292,9 @@ dependencies = [
  "frame-metadata 16.0.0",
  "hashbrown 0.14.5",
  "hex",
- "impl-serde",
+ "impl-serde 0.4.0",
  "parity-scale-codec",
- "primitive-types",
+ "primitive-types 0.12.2",
  "scale-bits",
  "scale-decode",
  "scale-encode",
@@ -25569,6 +25659,18 @@ dependencies = [
  "static_assertions",
 ]
 
+[[package]]
+name = "uint"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "909988d098b2f738727b161a106cfc7cab00c539c2687a8836f8e565976fb53e"
+dependencies = [
+ "byteorder",
+ "crunchy",
+ "hex",
+ "static_assertions",
+]
+
 [[package]]
 name = "unarray"
 version = "0.1.4"
diff --git a/Cargo.toml b/Cargo.toml
index e2c6d6c8dedc..9f5d98d04a12 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -742,8 +742,8 @@ env_logger = { version = "0.11.2" }
 environmental = { version = "1.1.4", default-features = false }
 equivocation-detector = { path = "bridges/relays/equivocation" }
 ethabi = { version = "1.0.0", default-features = false, package = "ethabi-decode" }
-ethbloom = { version = "0.13.0", default-features = false }
-ethereum-types = { version = "0.14.1", default-features = false }
+ethbloom = { version = "0.14.1", default-features = false }
+ethereum-types = { version = "0.15.1", default-features = false }
 exit-future = { version = "0.2.0" }
 expander = { version = "2.0.0" }
 fatality = { version = "0.1.1" }
@@ -1080,7 +1080,7 @@ polkavm-derive = "0.9.1"
 polkavm-linker = "0.9.2"
 portpicker = { version = "0.1.1" }
 pretty_assertions = { version = "1.3.0" }
-primitive-types = { version = "0.12.1", default-features = false }
+primitive-types = { version = "0.13.1", default-features = false, features = ["num-traits"] }
 proc-macro-crate = { version = "3.0.0" }
 proc-macro-warning = { version = "1.0.0", default-features = false }
 proc-macro2 = { version = "1.0.86" }
@@ -1108,7 +1108,7 @@ relay-substrate-client = { path = "bridges/relays/client-substrate" }
 relay-utils = { path = "bridges/relays/utils" }
 remote-externalities = { path = "substrate/utils/frame/remote-externalities", default-features = false, package = "frame-remote-externalities" }
 reqwest = { version = "0.11", default-features = false }
-rlp = { version = "0.5.2", default-features = false }
+rlp = { version = "0.6.1", default-features = false }
 rococo-emulated-chain = { path = "cumulus/parachains/integration-tests/emulated/chains/relays/rococo" }
 rococo-parachain-runtime = { path = "cumulus/parachains/runtimes/testing/rococo-parachain" }
 rococo-runtime = { path = "polkadot/runtime/rococo" }
diff --git a/prdoc/pr_5886.prdoc b/prdoc/pr_5886.prdoc
new file mode 100644
index 000000000000..94baa021e47a
--- /dev/null
+++ b/prdoc/pr_5886.prdoc
@@ -0,0 +1,16 @@
+title: Bump some dependencies
+doc:
+- audience: Runtime Dev
+  description: |-
+    This bumps `ethbloom`, `ethereum-types`, `primitive-types` and `rlp` to their latest version.
+
+    Fixes: https://github.com/paritytech/polkadot-sdk/issues/5870
+crates:
+- name: sc-consensus-babe
+  bump: patch
+- name: pallet-babe
+  bump: patch
+- name: pallet-revive
+  bump: patch
+- name: sp-runtime
+  bump: patch
diff --git a/substrate/client/consensus/babe/src/authorship.rs b/substrate/client/consensus/babe/src/authorship.rs
index 57ee706a04f6..06394b84f470 100644
--- a/substrate/client/consensus/babe/src/authorship.rs
+++ b/substrate/client/consensus/babe/src/authorship.rs
@@ -108,7 +108,8 @@ pub(super) fn secondary_slot_author(
 		return None
 	}
 
-	let rand = U256::from((randomness, slot).using_encoded(sp_crypto_hashing::blake2_256));
+	let rand =
+		U256::from_little_endian(&(randomness, slot).using_encoded(sp_crypto_hashing::blake2_256));
 
 	let authorities_len = U256::from(authorities.len());
 	let idx = rand % authorities_len;
diff --git a/substrate/frame/babe/src/mock.rs b/substrate/frame/babe/src/mock.rs
index 4e4052b2b566..d416e31b25f7 100644
--- a/substrate/frame/babe/src/mock.rs
+++ b/substrate/frame/babe/src/mock.rs
@@ -291,7 +291,7 @@ pub fn new_test_ext_with_pairs(
 	authorities_len: usize,
 ) -> (Vec<AuthorityPair>, sp_io::TestExternalities) {
 	let pairs = (0..authorities_len)
-		.map(|i| AuthorityPair::from_seed(&U256::from(i).into()))
+		.map(|i| AuthorityPair::from_seed(&U256::from(i).to_little_endian()))
 		.collect::<Vec<_>>();
 
 	let public = pairs.iter().map(|p| p.public()).collect();
diff --git a/substrate/frame/revive/src/wasm/runtime.rs b/substrate/frame/revive/src/wasm/runtime.rs
index 4b5a9a04eb73..8be68149834e 100644
--- a/substrate/frame/revive/src/wasm/runtime.rs
+++ b/substrate/frame/revive/src/wasm/runtime.rs
@@ -46,9 +46,7 @@ const MAX_DECODE_NESTING: u32 = 256;
 
 /// Encode a `U256` into a 32 byte buffer.
 fn as_bytes(u: U256) -> [u8; 32] {
-	let mut bytes = [0u8; 32];
-	u.to_little_endian(&mut bytes);
-	bytes
+	u.to_little_endian()
 }
 
 #[derive(Clone, Copy)]
diff --git a/substrate/frame/sassafras/src/mock.rs b/substrate/frame/sassafras/src/mock.rs
index f145bffa3a05..0bc71baa065b 100644
--- a/substrate/frame/sassafras/src/mock.rs
+++ b/substrate/frame/sassafras/src/mock.rs
@@ -89,7 +89,7 @@ pub fn new_test_ext_with_pairs(
 	with_ring_context: bool,
 ) -> (Vec<AuthorityPair>, sp_io::TestExternalities) {
 	let pairs = (0..authorities_len)
-		.map(|i| AuthorityPair::from_seed(&U256::from(i).into()))
+		.map(|i| AuthorityPair::from_seed(&U256::from(i).to_little_endian()))
 		.collect::<Vec<_>>();
 
 	let authorities: Vec<_> = pairs.iter().map(|p| p.public()).collect();
diff --git a/substrate/primitives/runtime/src/testing.rs b/substrate/primitives/runtime/src/testing.rs
index b4aeda5a0e7a..a4ce4b5fc1a0 100644
--- a/substrate/primitives/runtime/src/testing.rs
+++ b/substrate/primitives/runtime/src/testing.rs
@@ -29,10 +29,7 @@ use crate::{
 	ApplyExtrinsicResultWithInfo, KeyTypeId,
 };
 use serde::{de::Error as DeError, Deserialize, Deserializer, Serialize, Serializer};
-use sp_core::{
-	crypto::{key_types, ByteArray, CryptoType, Dummy},
-	U256,
-};
+use sp_core::crypto::{key_types, ByteArray, CryptoType, Dummy};
 pub use sp_core::{sr25519, H256};
 use std::{
 	cell::RefCell,
@@ -79,7 +76,8 @@ impl From<UintAuthorityId> for u64 {
 impl UintAuthorityId {
 	/// Convert this authority ID into a public key.
 	pub fn to_public_key<T: ByteArray>(&self) -> T {
-		let bytes: [u8; 32] = U256::from(self.0).into();
+		let mut bytes = [0u8; 32];
+		bytes[0..8].copy_from_slice(&self.0.to_le_bytes());
 		T::from_slice(&bytes).unwrap()
 	}
 }