diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4108ef8c2e..21e81036d7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -61,6 +61,12 @@ jobs:
       - name: Check build
         run: ENABLE_LINKCHECK=1 mdbook build
 
+      - name: Check build with link checking disabled
+        run: |
+          output=$(mktemp)
+          mdbook build 2>&1 | tee "$output"
+          ! grep -F "Broken pipe" "$output"
+
       - name: Save cached Linkcheck
         id: cache-linkcheck-save
         if: ${{ !cancelled() && github.event_name == 'schedule' }}
diff --git a/ci/linkcheck.sh b/ci/linkcheck.sh
index 867b427eaf..ae0373f911 100755
--- a/ci/linkcheck.sh
+++ b/ci/linkcheck.sh
@@ -11,6 +11,9 @@ set_github_token() {
 
 if [ -z "$ENABLE_LINKCHECK" ] ; then
   echo "Skipping link check."
+  # mdBook writes the render context to extensions over stdin.
+  # Discard it so mdBook doesn't warn about a broken pipe.
+  cat > /dev/null
   exit 0
 fi