diff --git a/.github/workflows/sphinx_asdf_ci.yml b/.github/workflows/sphinx_asdf_ci.yml
index 1ccbf1e..6e6b1ac 100644
--- a/.github/workflows/sphinx_asdf_ci.yml
+++ b/.github/workflows/sphinx_asdf_ci.yml
@@ -9,6 +9,14 @@ on:
   pull_request:
     branches:
 
+# Only cancel in-progress jobs or runs for the current workflow
+#   This cancels the already triggered workflows for a specific PR without canceling
+#   other instances of this workflow (other PRs, scheduled triggers, etc) when something
+#   within that PR re-triggers this CI
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   tox_pytest:
     name: ${{ matrix.name }}
diff --git a/sphinx_asdf/conf.py b/sphinx_asdf/conf.py
index 524e49f..c913565 100644
--- a/sphinx_asdf/conf.py
+++ b/sphinx_asdf/conf.py
@@ -1,3 +1,4 @@
+import datetime  # noqa: F401
 import os
 import sys