diff --git a/.github/workflows/pull-request.yaml b/.github/workflows/pull-request.yaml
index 2baad583..2249c44b 100644
--- a/.github/workflows/pull-request.yaml
+++ b/.github/workflows/pull-request.yaml
@@ -2,6 +2,10 @@ name: Pull Request
 
 on: pull_request
 
+env:
+  SCCACHE_GHA_ENABLED: "true"
+  RUSTC_WRAPPER: "sccache"
+
 jobs:
   check:
     name: Check Python
@@ -13,6 +17,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
+      - name: Run sccache-cache
+        uses: mozilla-actions/sccache-action@v0.0.3
       - name: Install poetry
         run: pipx install poetry
       - name: Set up Python ${{ matrix.python-version }}
@@ -39,16 +45,8 @@ jobs:
           src: "./guppylang"
           args: check
 
-      - name: Build Hugr validator
-        uses: PyO3/maturin-action@v1
-        with:
-          command: build
-          sccache: 'true'
-          rust-toolchain: '1.75'
-          working-directory: validator
-
-      - name: Install Hugr validator
-        run: poetry add validator/target/wheels/*
+      - name: Install Guppy with validation
+        run: poetry install --with validation
 
       - name: Run tests
         run: poetry run pytest
diff --git a/poetry.lock b/poetry.lock
index 45a4be9d..aab547c6 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -912,4 +912,4 @@ pytket = ["pytket", "tket2-py"]
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.10"
-content-hash = "7108630ba769a2e8e76da9f4aca911602ebd33f140501a2abb926d38ab20a076"
+content-hash = "38603201ab598596fc0671e329e91573b78f55f1420767cfbffae55a291fe32c"
diff --git a/pyproject.toml b/pyproject.toml
index 9dae04e6..b3cce387 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,6 +23,11 @@ pre-commit = "^3.6.0"
 ruff = "^0.1.11"
 maturin = "^1.4.0"
 pytket = "*"
+
+[tool.poetry.group.validation]
+optional = true
+
+[tool.poetry.group.validation.dependencies]
 guppyval = {path = "validator"}
 
 [tool.poetry.extras]