diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 1d5bc7d9..963748d1 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -14,21 +14,21 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
-      with:
-        submodules: true
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
 
-    - name: Install latest mdbook
-      run: |
-        tag=$(curl 'https://api.github.com/repos/rust-lang/mdbook/releases/latest' | jq -r '.tag_name')
-        url="https://github.com/rust-lang/mdbook/releases/download/${tag}/mdbook-${tag}-x86_64-unknown-linux-gnu.tar.gz"
-        mkdir bin
-        curl -sSL $url | tar -xz --directory=bin
-        echo "$(pwd)/bin" >> $GITHUB_PATH
+      - name: Install latest mdbook
+        run: |
+          tag=$(curl 'https://api.github.com/repos/rust-lang/mdbook/releases/latest' | jq -r '.tag_name')
+          url="https://github.com/rust-lang/mdbook/releases/download/${tag}/mdbook-${tag}-x86_64-unknown-linux-gnu.tar.gz"
+          mkdir bin
+          curl -sSL $url | tar -xz --directory=bin
+          echo "$(pwd)/bin" >> $GITHUB_PATH
 
-    - name: Build
-      run: cargo build --verbose --no-default-features
-    - name: Run tests
-      run: cargo test --no-default-features
-    - name: Run mdbook tests
-      run: mdbook test ./pywr-book
+      - name: Build
+        run: cargo build --verbose --no-default-features --features highs
+      - name: Run tests
+        run: cargo test --no-default-features --features highs
+      - name: Run mdbook tests
+        run: mdbook test ./pywr-book
diff --git a/pywr-core/Cargo.toml b/pywr-core/Cargo.toml
index 5bd95f1c..0fdc225f 100644
--- a/pywr-core/Cargo.toml
+++ b/pywr-core/Cargo.toml
@@ -18,20 +18,19 @@ libc = "0.2.97"
 thiserror = { workspace = true }
 ndarray = { workspace = true }
 num = { workspace = true }
-float-cmp = {  workspace = true }
+float-cmp = { workspace = true }
 hdf5 = { workspace = true }
 csv = { workspace = true }
 clp-sys = { path = "../clp-sys", version = "0.1.0" }
 ipm-ocl = { path = "../ipm-ocl", optional = true }
 ipm-simd = { path = "../ipm-simd", optional = true }
-tracing = {  workspace = true }
-highs-sys = {  git = "https://github.com/jetuk/highs-sys", branch="fix-build-libz-linking", optional = true }
-# highs-sys = { path = "../../highs-sys" }
+tracing = { workspace = true }
+highs-sys = { version = "1.6.2", optional = true }
 nalgebra = "0.32.3"
 chrono = { workspace = true }
 polars = { workspace = true }
 
-pyo3 = {  workspace = true, features = ["chrono"] }
+pyo3 = { workspace = true, features = ["chrono"] }
 
 
 rayon = "1.6.1"
diff --git a/pywr-core/src/solvers/builder.rs b/pywr-core/src/solvers/builder.rs
index e644076e..2bdc2715 100644
--- a/pywr-core/src/solvers/builder.rs
+++ b/pywr-core/src/solvers/builder.rs
@@ -293,6 +293,14 @@ where
         I::from(self.builder.col_upper.len()).unwrap()
     }
 
+    pub fn num_rows(&self) -> I {
+        I::from(self.builder.row_upper.len()).unwrap()
+    }
+
+    pub fn num_non_zero(&self) -> I {
+        I::from(self.builder.elements.len()).unwrap()
+    }
+
     pub fn col_lower(&self) -> &[f64] {
         &self.builder.col_lower
     }
@@ -313,6 +321,10 @@ where
         &self.builder.row_upper
     }
 
+    pub fn row_mask(&self) -> &[I] {
+        &self.builder.row_mask
+    }
+
     pub fn row_starts(&self) -> &[I] {
         &self.builder.row_starts
     }
diff --git a/pywr-core/src/solvers/highs/settings.rs b/pywr-core/src/solvers/highs/settings.rs
index 939bc26f..6f3e01aa 100644
--- a/pywr-core/src/solvers/highs/settings.rs
+++ b/pywr-core/src/solvers/highs/settings.rs
@@ -39,14 +39,11 @@ impl HighsSolverSettings {
 ///
 /// ```
 /// use std::num::NonZeroUsize;
-/// use pywr::solvers::ClpSolverSettingsBuilder;
+/// use pywr_core::solvers::HighsSolverSettingsBuilder;
 /// // Settings with parallel enabled and 4 threads.
-/// let settings = ClpSolverSettingsBuilder::default().parallel().threads(4).build();
-///
-/// let mut builder = ClpSolverSettingsBuilder::default();
-/// builder.chunk_size(NonZeroUsize::new(1024).unwrap());
-/// let settings = builder.build();
+/// let settings = HighsSolverSettingsBuilder::default().parallel().threads(4).build();
 ///
+/// let mut builder = HighsSolverSettingsBuilder::default();
 /// builder.parallel();
 /// let settings = builder.build();
 ///
@@ -97,6 +94,6 @@ mod tests {
         };
         let settings_from_builder = HighsSolverSettingsBuilder::default().parallel().build();
 
-        assert_eq!(settings_from_builder, settings_from_builder);
+        assert_eq!(settings_from_builder, settings);
     }
 }