diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 81a72f1f68..98b47130a1 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -693,6 +693,12 @@ jobs:
         with:
           path: synapse
 
+      # Log Docker system info for debugging (compare with your local environment) and
+      # tracking GitHub runner changes over time (can easily compare a run from last
+      # week with the current one in question).
+      - run: docker system info
+        shell: bash
+
       - name: Install Rust
         uses: dtolnay/rust-toolchain@e97e2d8cc328f1b50210efc529dca0028893a2d9 # master
         with:
diff --git a/changelog.d/19480.misc b/changelog.d/19480.misc
new file mode 100644
index 0000000000..60abe04962
--- /dev/null
+++ b/changelog.d/19480.misc
@@ -0,0 +1 @@
+Log `docker system info` in CI so we have a plain record of how GitHub runners evolve over time.