diff --git a/Cargo.lock b/Cargo.lock
index 466979cca512..a23db1a8fcbe 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4145,8 +4145,6 @@ name = "cumulus-primitives-timestamp"
 version = "0.15.0"
 dependencies = [
  "cumulus-primitives-core",
- "futures",
- "parity-scale-codec",
  "sp-inherents",
  "sp-timestamp",
 ]
@@ -8380,9 +8378,9 @@ dependencies = [
 
 [[package]]
 name = "memchr"
-version = "2.6.4"
+version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f665ee40bc4a3c5590afb1e9677db74a508659dfd71e126420da8274909a0167"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
 [[package]]
 name = "memfd"
@@ -18634,12 +18632,13 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.114"
+version = "1.0.121"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c5f09b1bd632ef549eaa9f60a1f8de742bdbc698e6cee2095fc84dde5f549ae0"
+checksum = "4ab380d7d9f22ef3f21ad3e6c1ebe8e4fc7a2000ccba2e4d71fc96f15b2cb609"
 dependencies = [
  "indexmap 2.2.3",
  "itoa",
+ "memchr",
  "ryu",
  "serde",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 35913e86d62e..ae2a8f79c055 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1165,7 +1165,7 @@ separator = { version = "0.4.1" }
 serde = { version = "1.0.197", default-features = false }
 serde-big-array = { version = "0.3.2" }
 serde_derive = { version = "1.0.117" }
-serde_json = { version = "1.0.114", default-features = false }
+serde_json = { version = "1.0.121", default-features = false }
 serde_yaml = { version = "0.9" }
 serial_test = { version = "2.0.0" }
 sha1 = { version = "0.10.6" }
diff --git a/cumulus/primitives/timestamp/Cargo.toml b/cumulus/primitives/timestamp/Cargo.toml
index 6eeec50b36fe..c42e2126c0a7 100644
--- a/cumulus/primitives/timestamp/Cargo.toml
+++ b/cumulus/primitives/timestamp/Cargo.toml
@@ -10,16 +10,16 @@ license = "Apache-2.0"
 workspace = true
 
 [dependencies]
-codec = { features = ["derive"], workspace = true }
-futures = { workspace = true }
-sp-inherents.workspace = true
-sp-timestamp.workspace = true
-cumulus-primitives-core.workspace = true
+# Substrate
+sp-inherents = { workspace = true }
+sp-timestamp = { workspace = true }
+
+# Cumulus
+cumulus-primitives-core = { workspace = true }
 
 [features]
 default = ["std"]
 std = [
-	"codec/std",
 	"cumulus-primitives-core/std",
 	"sp-inherents/std",
 	"sp-timestamp/std",
diff --git a/prdoc/pr_5367.prdoc b/prdoc/pr_5367.prdoc
new file mode 100644
index 000000000000..a87d2bdcdc41
--- /dev/null
+++ b/prdoc/pr_5367.prdoc
@@ -0,0 +1,13 @@
+# Schema: Polkadot SDK PRDoc Schema (prdoc) v1.0.0
+# See doc at https://raw.githubusercontent.com/paritytech/polkadot-sdk/master/prdoc/schema_user.json
+
+title: Fixes `std` leaking into the WASM runtime build
+
+doc:
+  - audience: Runtime Dev
+    description: |
+      Fixes `std` leaking into the WASM runtime build when updating `serde_json`.
+
+crates:
+  - name: cumulus-primitives-timestamp
+    bump: patch