diff --git a/Cargo.toml b/Cargo.toml
index 29ce91aa..fc07a6dd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,7 +17,7 @@ license-file = "LICENCE"
 [workspace.dependencies]
 
 tket2 = { path = "./tket2" }
-quantinuum-hugr = { git = "https://github.com/CQCL-DEV/hugr", rev = "1fce927" }
+quantinuum-hugr = { git = "https://github.com/CQCL-DEV/hugr", rev = "b71cae6" }
 portgraph = { version = "0.10" }
 pyo3 = { version = "0.20" }
 itertools = { version = "0.11.0" }
diff --git a/tket2/src/circuit.rs b/tket2/src/circuit.rs
index 7e46563d..d8e55577 100644
--- a/tket2/src/circuit.rs
+++ b/tket2/src/circuit.rs
@@ -38,8 +38,7 @@ pub trait Circuit: HugrView {
     /// Return the name of the circuit
     #[inline]
     fn name(&self) -> Option<&str> {
-        let meta = self.get_metadata(self.root()).as_object()?;
-        meta.get("name")?.as_str()
+        self.get_metadata(self.root(), "name")?.as_str()
     }
 
     /// Returns the function type of the circuit.
diff --git a/tket2/src/json/decoder.rs b/tket2/src/json/decoder.rs
index 6a02e297..2721dfb6 100644
--- a/tket2/src/json/decoder.rs
+++ b/tket2/src/json/decoder.rs
@@ -73,14 +73,14 @@ impl JsonDecoder {
 
         // Metadata. The circuit requires "name", and we store other things that
         // should pass through the serialization roundtrip.
-        let metadata = json!({
-            "name": serialcirc.name,
-            METADATA_PHASE: serialcirc.phase,
-            METADATA_IMPLICIT_PERM: serialcirc.implicit_permutation,
-            METADATA_Q_REGISTERS: serialcirc.qubits,
-            METADATA_B_REGISTERS: serialcirc.bits,
-        });
-        dfg.set_metadata(metadata);
+        dfg.set_metadata("name", json!(serialcirc.name));
+        dfg.set_metadata(METADATA_PHASE, json!(serialcirc.phase));
+        dfg.set_metadata(
+            METADATA_IMPLICIT_PERM,
+            json!(serialcirc.implicit_permutation),
+        );
+        dfg.set_metadata(METADATA_Q_REGISTERS, json!(serialcirc.qubits));
+        dfg.set_metadata(METADATA_B_REGISTERS, json!(serialcirc.bits));
 
         let dangling_wires = dfg.input_wires().collect::<Vec<_>>();
         JsonDecoder {
diff --git a/tket2/src/json/encoder.rs b/tket2/src/json/encoder.rs
index e6a0d136..f3ea1273 100644
--- a/tket2/src/json/encoder.rs
+++ b/tket2/src/json/encoder.rs
@@ -57,21 +57,19 @@ impl JsonEncoder {
         let mut implicit_permutation = vec![];
 
         // Recover other parameters stored in the metadata
-        if let Some(meta) = circ.get_metadata(circ.root()).as_object() {
-            if let Some(p) = meta.get(METADATA_PHASE) {
-                // TODO: Check for invalid encoded metadata
-                phase = p.as_str().unwrap().to_string();
-            }
-            if let Some(perm) = meta.get(METADATA_IMPLICIT_PERM) {
-                // TODO: Check for invalid encoded metadata
-                implicit_permutation = serde_json::from_value(perm.clone()).unwrap();
-            }
-            if let Some(q_regs) = meta.get(METADATA_Q_REGISTERS) {
-                qubit_registers = serde_json::from_value(q_regs.clone()).unwrap();
-            }
-            if let Some(b_regs) = meta.get(METADATA_B_REGISTERS) {
-                bit_registers = serde_json::from_value(b_regs.clone()).unwrap();
-            }
+        // TODO: Check for invalid encoded metadata
+        let root = circ.root();
+        if let Some(p) = circ.get_metadata(root, METADATA_PHASE) {
+            phase = p.as_str().unwrap().to_string();
+        }
+        if let Some(perm) = circ.get_metadata(root, METADATA_IMPLICIT_PERM) {
+            implicit_permutation = serde_json::from_value(perm.clone()).unwrap();
+        }
+        if let Some(q_regs) = circ.get_metadata(root, METADATA_Q_REGISTERS) {
+            qubit_registers = serde_json::from_value(q_regs.clone()).unwrap();
+        }
+        if let Some(b_regs) = circ.get_metadata(root, METADATA_B_REGISTERS) {
+            bit_registers = serde_json::from_value(b_regs.clone()).unwrap();
         }
 
         // Map the Hugr units to tket1 register names.
diff --git a/tket2/src/passes/chunks.rs b/tket2/src/passes/chunks.rs
index e15a6da5..bad25839 100644
--- a/tket2/src/passes/chunks.rs
+++ b/tket2/src/passes/chunks.rs
@@ -12,7 +12,7 @@ use hugr::extension::ExtensionSet;
 use hugr::hugr::hugrmut::HugrMut;
 use hugr::hugr::views::sibling_subgraph::ConvexChecker;
 use hugr::hugr::views::{HierarchyView, SiblingGraph, SiblingSubgraph};
-use hugr::hugr::{HugrError, NodeMetadata};
+use hugr::hugr::{HugrError, NodeMetadataMap};
 use hugr::ops::handle::DataflowParentID;
 use hugr::ops::OpType;
 use hugr::types::{FunctionType, Signature};
@@ -247,7 +247,7 @@ pub struct CircuitChunks {
     signature: FunctionType,
 
     /// The original circuit's root metadata.
-    root_meta: NodeMetadata,
+    root_meta: Option<NodeMetadataMap>,
 
     /// The original circuit's inputs.
     input_connections: Vec<ChunkConnection>,
@@ -275,7 +275,7 @@ impl CircuitChunks {
         max_cost: C,
         op_cost: impl Fn(&OpType) -> C,
     ) -> Self {
-        let root_meta = circ.get_metadata(circ.root()).clone();
+        let root_meta = circ.get_node_metadata(circ.root()).cloned();
         let signature = circ.circuit_signature().clone();
 
         let [circ_input, circ_output] = circ.get_io(circ.root()).unwrap();
@@ -318,8 +318,9 @@ impl CircuitChunks {
     pub fn reassemble(self) -> Result<Hugr, HugrError> {
         let name = self
             .root_meta
-            .get("name")
-            .and_then(|v| v.as_str())
+            .as_ref()
+            .and_then(|map| map.get("name"))
+            .and_then(|s| s.as_str())
             .unwrap_or("");
         let signature = Signature {
             signature: self.signature,
@@ -437,7 +438,7 @@ impl CircuitChunks {
             }
         }
 
-        reassembled.set_metadata(root, self.root_meta)?;
+        reassembled.overwrite_node_metadata(root, self.root_meta)?;
 
         Ok(reassembled)
     }