diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c3f830a5aa..6afb8a9d22 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -545,24 +545,29 @@ jobs:
           fetch-depth: 2
 
       - name: Restore Python
+        id: restore-python
         uses: ./.github/actions/restore-python
         with:
           python-version: ${{ env.DEFAULT_PYTHON }}
           cache-key: ${{ needs.common.outputs.cache-key }}
 
+      # Key on the exact Python version as well: LibreTiny creates a venv under
+      # ~/.platformio/penv whose interpreter is a symlink into the runner's
+      # hosted toolcache, so a cache saved on an older runner image breaks once
+      # a new image ships a newer patch release and drops the old interpreter.
       - name: Cache platformio
         if: github.ref == 'refs/heads/dev' && matrix.pio_cache_key
         uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
           path: ~/.platformio
-          key: platformio-${{ matrix.pio_cache_key }}-${{ hashFiles('platformio.ini') }}
+          key: platformio-${{ matrix.pio_cache_key }}-${{ steps.restore-python.outputs.python-version }}-${{ hashFiles('platformio.ini') }}
 
       - name: Cache platformio
         if: github.ref != 'refs/heads/dev' && matrix.pio_cache_key
         uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
           path: ~/.platformio
-          key: platformio-${{ matrix.pio_cache_key }}-${{ hashFiles('platformio.ini') }}
+          key: platformio-${{ matrix.pio_cache_key }}-${{ steps.restore-python.outputs.python-version }}-${{ hashFiles('platformio.ini') }}
 
       - name: Cache ESP-IDF install
         if: matrix.cache_idf