diff --git a/.gitlab-ci/pipeline.yml b/.gitlab-ci/pipeline.yml
index 398bb2552607a3c45e47128530fa52f221c739b4..f69fff8e3ada8a1285a135c68428fe781554a4df 100644
--- a/.gitlab-ci/pipeline.yml
+++ b/.gitlab-ci/pipeline.yml
@@ -134,24 +134,24 @@ variables:
     - git fetch -vn --depth=3 "$CI_MERGE_REQUEST_PROJECT_URL" "+refs/heads/$TARGET_BRANCH:refs/heads/$TARGET_BRANCH"
     - |
       echo "ℹ️ Changes from ${TARGET_BRANCH}"
-      git diff refs/heads/${TARGET_BRANCH} --name-only
+      git diff ${CI_MERGE_REQUEST_DIFF_BASE_SHA} --name-only
       echo "If this list contains more files than what you changed, then you need to rebase your branch."
       echo "1️⃣ Reverting non test changes"
-      if [[ $(git diff refs/heads/${TARGET_BRANCH} --diff-filter=DM --name-only|grep -Ev "Test.php$"|grep -v .gitlab-ci|grep -v scripts/run-tests.sh) ]]; then
-        git diff refs/heads/${TARGET_BRANCH} --diff-filter=DM --name-only|grep -Ev "Test.php$"|grep -v .gitlab-ci|grep -v scripts/run-tests.sh|while read file;do
+      if [[ $(git diff ${CI_MERGE_REQUEST_DIFF_BASE_SHA} --diff-filter=DM --name-only|grep -Ev "Test.php$"|grep -v .gitlab-ci|grep -v scripts/run-tests.sh) ]]; then
+        git diff ${CI_MERGE_REQUEST_DIFF_BASE_SHA} --diff-filter=DM --name-only|grep -Ev "Test.php$"|grep -v .gitlab-ci|grep -v scripts/run-tests.sh|while read file;do
           echo "↩️ Reverting $file";
           git checkout refs/heads/${TARGET_BRANCH} -- $file;
         done
       fi
-      if [[ $(git diff refs/heads/${TARGET_BRANCH} --diff-filter=A --name-only|grep -Ev "Test.php$"|grep -v .gitlab-ci|grep -v scripts/run-tests.sh) ]]; then
-        git diff refs/heads/${TARGET_BRANCH} --diff-filter=A --name-only|grep -Ev "Test.php$"|grep -v .gitlab-ci|grep -v scripts/run-tests.sh|while read file;do
+      if [[ $(git diff ${CI_MERGE_REQUEST_DIFF_BASE_SHA} --diff-filter=A --name-only|grep -Ev "Test.php$"|grep -v .gitlab-ci|grep -v scripts/run-tests.sh) ]]; then
+        git diff ${CI_MERGE_REQUEST_DIFF_BASE_SHA} --diff-filter=A --name-only|grep -Ev "Test.php$"|grep -v .gitlab-ci|grep -v scripts/run-tests.sh|while read file;do
           echo "🗑️️ Deleting $file";
           git rm $file;
         done
       fi
       echo "2️⃣ Running test changes for this branch"
-      if [[ $(git diff refs/heads/${TARGET_BRANCH} --name-only|grep -E "Test.php$") ]]; then
-        for test in `git diff refs/heads/${TARGET_BRANCH} --name-only|grep -E "Test.php$"`; do
+      if [[ $(git diff ${CI_MERGE_REQUEST_DIFF_BASE_SHA} --name-only|grep -E "Test.php$") ]]; then
+        for test in `git diff ${CI_MERGE_REQUEST_DIFF_BASE_SHA} --name-only|grep -E "Test.php$"`; do
           sudo SIMPLETEST_BASE_URL="$SIMPLETEST_BASE_URL" SIMPLETEST_DB="$SIMPLETEST_DB" MINK_DRIVER_ARGS_WEBDRIVER="$MINK_DRIVER_ARGS_WEBDRIVER" -u www-data ./vendor/bin/phpunit -c core $test --log-junit=./sites/default/files/simpletest/phpunit-`echo $test|sed 's/\//_/g' `.xml;
         done;
       fi