diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index bca5f5be..20d77d37 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -27,7 +27,7 @@ jobs:
         pip install -r requirements/test_requirements.txt
         pip install -r requirements/integration_test_requirements.txt -q
         # work around issues with GPy setting matplotlib backend
-        # echo 'backend: Agg' > matplotlibrc
+        echo 'backend: Agg' > matplotlibrc
         pip install .
     - name: Unit tests
       run: |
@@ -40,7 +40,7 @@ jobs:
 
     strategy:
       matrix:
-        os: [windows-latest]
+        os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
 
     steps:
@@ -52,11 +52,10 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install setuptools
         pip install -r requirements/requirements.txt
         pip install -r requirements/test_requirements.txt
         # work around issues with GPy setting matplotlib backend
-        # echo 'backend: Agg' > matplotlibrc
+        echo 'backend: Agg' > matplotlibrc
         pip install .
     - name: Unit tests
       run: |
diff --git a/requirements/requirements.txt b/requirements/requirements.txt
index d25de966..c1d11415 100644
--- a/requirements/requirements.txt
+++ b/requirements/requirements.txt
@@ -5,6 +5,6 @@ numpy>=1.23
 # This is unfortunate - we don't need matplotlib
 # but until GPy and GPyOpt get their dependencies straight
 # we need GPy's plotting extra to ensure smooth installation
-GPy>=1.13.0
+GPy[plotting]>=1.13.0
 emcee>=2.2.1
 scipy>=1.1.0