diff --git a/Cargo.lock b/Cargo.lock
index c5b8b3048..7f0e93e21 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -911,9 +911,9 @@ dependencies = [
 
 [[package]]
 name = "hugr"
-version = "0.15.2"
+version = "0.15.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f4ade13fa95ebd8d6ae071767a166f597b16505a56c011b9e21b9b09ef091eba"
+checksum = "61f76ba415cbd86242348c74abd0c67459f6d0e7fd26fb439c31e747d9aa45c8"
 dependencies = [
  "hugr-core",
  "hugr-passes",
@@ -921,9 +921,9 @@ dependencies = [
 
 [[package]]
 name = "hugr-cli"
-version = "0.15.2"
+version = "0.15.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "686d6a2eba2d5918b5f4aca3c23ef2b199f1b6d4b36271536dace703cb647ce8"
+checksum = "e2177be2f581e4a0cc65da513e7dc9e08c133e1a0abeb1877bbe482f2d737f77"
 dependencies = [
  "clap",
  "clap-verbosity-flag",
@@ -935,9 +935,9 @@ dependencies = [
 
 [[package]]
 name = "hugr-core"
-version = "0.15.2"
+version = "0.15.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b76e8761b2b58b4a4b533250efc289e6082e80e723383dd392d5192081ad7a8"
+checksum = "2ee45725211e15e414492d279be7bd84fdff0c4fad55aa1608ed40b47b7ad524"
 dependencies = [
  "cgmath",
  "delegate 0.13.3",
@@ -966,11 +966,12 @@ dependencies = [
 
 [[package]]
 name = "hugr-passes"
-version = "0.15.2"
+version = "0.15.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0d42ac5f02ce1e0c7d306ed20a5bc766409db09eada1c21fd9b308deda57110e"
+checksum = "f5ff7529467118342f26c30bf37079d30000d1542400eda435fc3758903ee820"
 dependencies = [
  "ascent",
+ "derive_more 1.0.0",
  "hugr-core",
  "itertools 0.14.0",
  "lazy_static",
diff --git a/Cargo.toml b/Cargo.toml
index 27a243dc0..74abfe8c6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -31,8 +31,8 @@ missing_docs = "warn"
 [patch.crates-io]
 
 # Uncomment to use unreleased versions of hugr
-# hugr = { git = "https://github.com/CQCL/hugr", rev = "4e6b6d8" }
-# hugr-core = { git = "https://github.com/CQCL/hugr", rev = "4e6b6d8" }
+# hugr = { git = "https://github.com/CQCL/hugr", rev = "167c687" }
+# hugr-core = { git = "https://github.com/CQCL/hugr", rev = "167c687" }
 # hugr-passes = { git = "https://github.com/CQCL/hugr", rev = "4e6b6d8" }
 # hugr-cli = { git = "https://github.com/CQCL/hugr", rev = "4e6b6d8" }
 # portgraph = { git = "https://github.com/CQCL/portgraph", rev = "68b96ac737e0c285d8c543b2d74a7aa80a18202c" }
@@ -40,9 +40,9 @@ missing_docs = "warn"
 [workspace.dependencies]
 
 # Make sure to run `just recompile-eccs` if the hugr serialisation format changes.
-hugr = "0.15.2"
-hugr-core = "0.15.0"
-hugr-cli = "0.15.2"
+hugr = "0.15.3"
+hugr-core = "0.15.3"
+hugr-cli = "0.15.3"
 portgraph = "0.13.3"
 pyo3 = "0.23.4"
 itertools = "0.14.0"
diff --git a/tket2-hseries/src/extension/qsystem.rs b/tket2-hseries/src/extension/qsystem.rs
index 5a6bde3ef..049abf631 100644
--- a/tket2-hseries/src/extension/qsystem.rs
+++ b/tket2-hseries/src/extension/qsystem.rs
@@ -414,7 +414,9 @@ pub trait QSystemOpBuilder: Dataflow + UnwrapBuilder {
     /// Build a qalloc operation that panics on failure.
     fn build_qalloc(&mut self) -> Result<Wire, BuildError> {
         let maybe_qb = self.add_try_alloc()?;
-        let [qb] = self.build_unwrap_sum(1, option_type(qb_t()), maybe_qb)?;
+        let [qb] = self.build_expect_sum(1, option_type(qb_t()), maybe_qb, |_| {
+            "No more qubits available to allocate.".to_string()
+        })?;
         Ok(qb)
     }
 }
diff --git a/tket2/src/extension/bool.rs b/tket2/src/extension/bool.rs
index 05cbe65a7..07336a6b3 100644
--- a/tket2/src/extension/bool.rs
+++ b/tket2/src/extension/bool.rs
@@ -219,14 +219,14 @@ pub trait BoolOpBuilder: Dataflow {
             .outputs_arr())
     }
 
-    /// Add a "tket2.bool.Or" op.   
+    /// Add a "tket2.bool.Or" op.
     fn add_or(&mut self, bool1: Wire, bool2: Wire) -> Result<[Wire; 1], BuildError> {
         Ok(self
             .add_dataflow_op(BoolOp::or, [bool1, bool2])?
             .outputs_arr())
     }
 
-    /// Add a "tket2.bool.Xor" op.          
+    /// Add a "tket2.bool.Xor" op.
     fn add_xor(&mut self, bool1: Wire, bool2: Wire) -> Result<[Wire; 1], BuildError> {
         Ok(self
             .add_dataflow_op(BoolOp::xor, [bool1, bool2])?