diff --git a/.github/workflows/mdbook.yml b/.github/workflows/mdbook.yml
index 60b4857..ccd4756 100644
--- a/.github/workflows/mdbook.yml
+++ b/.github/workflows/mdbook.yml
@@ -45,7 +45,7 @@ jobs:
     steps:
       # inputs.ref is only set for manual backfills; push-to-main and tag-push events
       # default to the triggering ref automatically
-      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5  # v4.3.1
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10  # v6.0.3
         with:
           persist-credentials: false
           ref: ${{ inputs.ref }}
diff --git a/.github/workflows/zizmor.yml b/.github/workflows/zizmor.yml
index e74b66a..aa0c18f 100644
--- a/.github/workflows/zizmor.yml
+++ b/.github/workflows/zizmor.yml
@@ -22,7 +22,7 @@ jobs:
       actions: read
     steps:
       - name: Checkout repository
-        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5  # v4.3.1
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10  # v6.0.3
         with:
           persist-credentials: false