diff --git a/.config/ci/check_commits.sh b/.config/ci/check_commits.sh
index f5efc667c48..8ca9bc16bc8 100755
--- a/.config/ci/check_commits.sh
+++ b/.config/ci/check_commits.sh
@@ -6,7 +6,14 @@
 # We copy Wireshark's contributing guide, thanks to them for the idea !
 # This script is inspired by https://gitlab.com/wireshark/wireshark/-/blob/master/.gitlab-ci.yml
 
-commits=$(git rev-list --no-merges --after="2026-01-00T00:00:00" --max-count=$((PR_FETCH_DEPTH - 1)) HEAD)
+# On pull_request, actions/checkout creates a merge of the PR into the base
+# branch (HEAD^1=base tip, HEAD^2=PR tip). Restrict the check to PR commits
+# so base-branch history is not false-failed for missing trailers.
+if git rev-parse -q --verify HEAD^2 >/dev/null 2>&1; then
+    commits=$(git rev-list --no-merges HEAD^1..HEAD^2)
+else
+    commits=$(git rev-list --no-merges --after="2026-01-00T00:00:00" --max-count=$((PR_FETCH_DEPTH - 1)) HEAD)
+fi
 if [ -z "$commits" ]; then
     echo "No commit to check in PR. OK."
     exit 0