diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 172b26b0e52f2ff8076d4193ebe0f7c9722bbb9f..d1e41484ba67df31b5d115e6ec1ec9d8f49f47a9 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -127,8 +127,10 @@ test-python:
 
 test-dco-check:
     stage: test
+    dependencies: []
     script:
+    -   if [ -z "$CI_COMMIT_BRANCH" ] && [ "$CI_MERGE_REQUEST_SOURCE_PROJECT_PATH" != "$CI_MERGE_REQUEST_PROJECT_PATH" ]; then export CI_COMMIT_BRANCH="$CI_MERGE_REQUEST_SOURCE_PROJECT_PATH:$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME"; fi
     -   if [ -z "$CI_COMMIT_BRANCH" ]; then export CI_COMMIT_BRANCH="$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME"; fi
-    -   if [ -z "$CI_MERGE_REQUEST_TARGET_BRANCH_SHA" ]; then export CI_MERGE_REQUEST_TARGET_BRANCH_SHA=$(git merge-base --fork-point origin/$CI_MERGE_REQUEST_TARGET_BRANCH_NAME); fi
+    -   if [ -z "$CI_MERGE_REQUEST_TARGET_BRANCH_SHA" ] && [ -n "$CI_MERGE_REQUEST_DIFF_BASE_SHA" ]; then export CI_MERGE_REQUEST_TARGET_BRANCH_SHA="$CI_MERGE_REQUEST_DIFF_BASE_SHA"; fi
     -   pip install dco-check
     -   dco-check