diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 6c46e85134..fafa95796b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -58,12 +58,12 @@ jobs:
           rm -rf firedrake_venv
       - name: Build Firedrake
         run: |
+          unset PETSC_DIR PETSC_ARCH SLEPC_DIR
           cd ..
           # Linting should ignore unquoted shell variable $COMPLEX
           # shellcheck disable=SC2086
           ./firedrake/scripts/firedrake-install \
             $COMPLEX \
-            --honour-petsc-dir \
             --mpicc="$MPICH_DIR"/mpicc \
             --mpicxx="$MPICH_DIR"/mpicxx \
             --mpif90="$MPICH_DIR"/mpif90 \
@@ -87,6 +87,8 @@ jobs:
             --install asQ \
             --package-branch tsfc ksagiyam/introduce_mixed_map \
             --package-branch ufl ksagiyam/introduce_mixed_map \
+            --package-branch petsc ksagiyam/merge_upstream \
+            --package-branch slepc ksagiyam/merge_upstream \
             || (cat firedrake-install.log && /bin/false)
       - name: Install test dependencies
         run: |
@@ -97,6 +99,7 @@ jobs:
           python -m pip list
       - name: Test Firedrake
         run: |
+          unset PETSC_DIR PETSC_ARCH SLEPC_DIR
           . ../firedrake_venv/bin/activate
           echo OMP_NUM_THREADS is "$OMP_NUM_THREADS"
           echo OPENBLAS_NUM_THREADS is "$OPENBLAS_NUM_THREADS"
@@ -113,6 +116,7 @@ jobs:
       - name: Test pyadjoint
         if: ${{ matrix.scalar-type == 'real' }}
         run: |
+          unset PETSC_DIR PETSC_ARCH SLEPC_DIR
           . ../firedrake_venv/bin/activate
           cd ../firedrake_venv/src/pyadjoint
           python -m pytest \
diff --git a/docs/notebooks/08-composable-solvers.ipynb b/docs/notebooks/08-composable-solvers.ipynb
index ccc42c43d2..91497d62f1 100644
--- a/docs/notebooks/08-composable-solvers.ipynb
+++ b/docs/notebooks/08-composable-solvers.ipynb
@@ -1236,10 +1236,10 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "#w.assign(0)\n",
-    "#solver = create_solver(vanka_parameters)\n",
-    "#solver.solve()\n",
-    "#convergence(solver)"
+    "w.assign(0)\n",
+    "solver = create_solver(vanka_parameters)\n",
+    "solver.solve()\n",
+    "convergence(solver)"
    ]
   },
   {