diff --git a/Cargo.lock b/Cargo.lock
index 5853ec9a..82aecc0e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1780,9 +1780,9 @@ checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"
 
 [[package]]
 name = "tket-json-rs"
-version = "0.4.1"
+version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f62807960274a10068c64b213795f0009027c534ffe48924ca2e12d09acad8e7"
+checksum = "b2ca98b0f30f8dfb05a77081305b34891e2362331253cb9bf3c10efa879dbbb3"
 dependencies = [
  "pyo3",
  "pythonize",
diff --git a/Cargo.toml b/Cargo.toml
index 4ce344b8..ffde4770 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -31,7 +31,7 @@ hugr-core = "0.2.0"
 portgraph = "0.12"
 pyo3 = "0.21.2"
 itertools = "0.13.0"
-tket-json-rs = "0.4.0"
+tket-json-rs = "0.4.2"
 tracing = "0.1.37"
 portmatching = "0.3.1"
 bytemuck = "1.16.1"