diff --git a/.github/workflows/pip.yml b/.github/workflows/pip.yml
index 0ba7007e99..c358b70141 100644
--- a/.github/workflows/pip.yml
+++ b/.github/workflows/pip.yml
@@ -62,17 +62,16 @@ jobs:
           python -m pip install 'rtree>=1.2'
           cd pip_venv/src
           git clone https://github.com/firedrakeproject/libsupermesh.git
-          cd libsupermesh
-          mkdir -p build
-          cd build
+          mkdir -p libsupermesh/build
+          cd libsupermesh/build
           cmake .. \
             -DBUILD_SHARED_LIBS=ON \
-            -DCMAKE_INSTALL_PREFIX=$VIRTUAL_ENV \
-            -DMPI_C_COMPILER=$MPICH_DIR/mpicc \
-            -DMPI_CXX_COMPILER=$MPICH_DIR/mpicxx \
-            -DMPI_Fortran_COMPILER=$MPICH_DIR/mpif90 \
-            -DCMAKE_Fortran_COMPILER=$MPICH_DIR/mpif90 \
-            -DMPIEXEC_EXECUTABLE=$MPICH_DIR/mpiexec
+            -DCMAKE_INSTALL_PREFIX="$VIRTUAL_ENV" \
+            -DMPI_C_COMPILER="$MPICH_DIR/mpicc" \
+            -DMPI_CXX_COMPILER="$MPICH_DIR/mpicxx" \
+            -DMPI_Fortran_COMPILER="$MPICH_DIR/mpif90" \
+            -DCMAKE_Fortran_COMPILER="$MPICH_DIR/mpif90" \
+            -DMPIEXEC_EXECUTABLE="$MPICH_DIR/mpiexec"
           make
           make install
 
diff --git a/.github/workflows/pyop2.yml b/.github/workflows/pyop2.yml
index 4d0ce1dd64..7248f195b3 100644
--- a/.github/workflows/pyop2.yml
+++ b/.github/workflows/pyop2.yml
@@ -39,6 +39,10 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
 
+      - name: Prepare venv
+        run: |
+          python -m venv venv
+
       - name: Clone PETSc
         uses: actions/checkout@v4
         with:
@@ -57,6 +61,24 @@ jobs:
             --with-fortran-bindings=0
           make
 
+      - name: Install libsupermesh
+        run: |
+          source venv/bin/activate
+          python -m pip install 'rtree>=1.2'
+          git clone https://github.com/firedrakeproject/libsupermesh.git
+          mkdir -p libsupermesh/build
+          cd libsupermesh/build
+          cmake .. \
+            -DBUILD_SHARED_LIBS=ON \
+            -DCMAKE_INSTALL_PREFIX="$VIRTUAL_ENV" \
+            -DMPI_C_COMPILER=mpicc \
+            -DMPI_CXX_COMPILER=mpicxx \
+            -DMPI_Fortran_COMPILER=mpif90 \
+            -DCMAKE_Fortran_COMPILER=mpif90 \
+            -DMPIEXEC_EXECUTABLE=mpiexec
+          make
+          make install
+
       - name: Checkout PyOP2
         uses: actions/checkout@v4
         with:
@@ -66,18 +88,22 @@ jobs:
         shell: bash
         working-directory: PyOP2
         run: |
+          source venv/bin/activate
           python -m pip install -U pip
           python -m pip install -U pytest-timeout
 
       - name: Install PyOP2
         shell: bash
         working-directory: PyOP2
-        run: python -m pip install -v ".[test]"
+        run: |
+          source venv/bin/activate
+          python -m pip install -v ".[test]"
 
       - name: Run tests
         shell: bash
         working-directory: PyOP2
         run: |
+          source venv/bin/activate
           # Running parallel test cases separately works around a bug in pytest-mpi
           pytest -k "not parallel" --tb=native --timeout=480 --timeout-method=thread -o faulthandler_timeout=540 -v tests/pyop2
           mpiexec -n 3 pytest -k "parallel[3]" --tb=native --timeout=480 --timeout-method=thread -o faulthandler_timeout=540 -v tests/pyop2
diff --git a/setup.py b/setup.py
index 21ab9f28ab..2ab024be27 100644
--- a/setup.py
+++ b/setup.py
@@ -156,8 +156,8 @@ def __getitem__(self, key):
 #    -lsupermesh \
 #    -Wl,-rpath,$ORIGIN/../../supermesh
 supermesh_ = ExternalDependency(
-    include_dirs=[sys.prefix],
-    library_dirs=[sys.prefix],
+    include_dirs=[f"{sys.prefix}/include"],
+    library_dirs=[f"{sys.prefix}/lib"],
     libraries=["supermesh"],
 )