diff --git a/dist/tools/ci/static_tests.sh b/dist/tools/ci/static_tests.sh
index ca0cf73961..13002560ad 100755
--- a/dist/tools/ci/static_tests.sh
+++ b/dist/tools/ci/static_tests.sh
@@ -51,19 +51,26 @@ function run {
 
 RESULT=0
 
+if [ -n "${CI_BASE_COMMIT}" ]; then
+    # on Murdock, there's no base branch in the checkout folder.
+    # Thus, tag it here.
+    echo "-- tagging ${CI_BASE_BRANCH} HEAD commit (${CI_BASE_COMMIT})"
+    git tag "${CI_BASE_BRANCH}" "${CI_BASE_COMMIT}"
+fi
+
 CI_BASE_BRANCH=${CI_BASE_BRANCH:-master}
 
 export BASE_BRANCH="${CI_BASE_BRANCH}"
 
-run ./dist/tools/commit-msg/check.sh "${CI_BASE_BRANCH}"
-run ./dist/tools/whitespacecheck/check.sh "${CI_BASE_BRANCH}"
+run ./dist/tools/commit-msg/check.sh "${BASE_BRANCH}"
+run ./dist/tools/whitespacecheck/check.sh "${BASE_BRANCH}"
 DIFFFILTER="MR" ERROR_EXIT_CODE=0 run ./dist/tools/licenses/check.sh
 DIFFFILTER="AC" run ./dist/tools/licenses/check.sh
 run ./dist/tools/doccheck/check.sh
 run ./dist/tools/externc/check.sh
 run ./dist/tools/cppcheck/check.sh
 run ./dist/tools/vera++/check.sh
-run ./dist/tools/pr_check/pr_check.sh "${CI_BASE_BRANCH}"
+run ./dist/tools/pr_check/pr_check.sh "${BASE_BRANCH}"
 run ./dist/tools/coccinelle/check.sh
 run ./dist/tools/flake8/check.sh
 run ./dist/tools/headerguards/check.sh