diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 8736699ad..fa9c5e036 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -192,6 +192,7 @@ jobs:
       volumes:
         - ${{ github.workspace }}:/src
       env:
+        SYTEST_BRANCH: ${{ github.head_ref }}
         POSTGRES: ${{ matrix.postgres && 1}}
         MULTI_POSTGRES: ${{ (matrix.postgres == 'multi-postgres') && 1}}
         WORKERS: ${{ matrix.workers && 1 }}
diff --git a/changelog.d/10659.misc b/changelog.d/10659.misc
new file mode 100644
index 000000000..d677a521c
--- /dev/null
+++ b/changelog.d/10659.misc
@@ -0,0 +1 @@
+Fix GitHub Actions config so we can run sytest on synapse from parallel branches.
\ No newline at end of file