diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index bf73ffd..65e3191 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -9,6 +9,12 @@ jobs:
     strategy:
       matrix:
         python-version: ['3.11', '3.12', '3.13', '3.14', '3.15.0-rc.3']
+        # The floor of pyproject.toml's `httpx==0.28.*` / `pytest==9.*`, which no
+        # other entry installs: bump these pins when those ranges move.
+        lowest: ['']
+        include:
+          - python-version: '3.11'
+            lowest: '"httpx==0.28.0" "pytest==9.0.0"'
 
     steps:
     - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -19,7 +25,7 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install pip==26.2.1
-        python -m pip install -e .[testing]
+        python -m pip install ${{ matrix.lowest }} -e .[testing]
         python -m pip install pre-commit==4.6.2
     - name: Ensure pre-commit was applied
       run: |