diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 6d43228d71717a950fbc054118c6707cdec8ae2e..2136884d61abb9493275998623b6148d6b46b4e0 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -27,7 +27,7 @@ verify:
   stage: verify
   script:
     - mvn $MAVEN_CLI_OPTS verify site
-    - mvn $MAVEN_CLI_OPTS sonar:sonar
+    - test -z "$SONAR_TOKEN" || mvn $MAVEN_CLI_OPTS sonar:sonar
           -Dsonar.login=${SONAR_TOKEN}
           -Dsonar.branch.name=${CI_COMMIT_REF_NAME}
           -Dsonar.projectKey="$SONAR_PROJECT_KEY"
@@ -40,6 +40,15 @@ verify:
       junit:
         - target/surefire-reports/*.xml
 
+verify:warning:
+  stage: verify
+  script:
+    - echo "Please, configure SonarQube!"
+    - exit 1
+  allow_failure: true
+  rules:
+    - if: $SONAR_TOKEN == null
+
 # Convert and import in GitLab coverage data.
 # The information is then available directly in merge-request view.
 # Cf. https://docs.gitlab.com/ee/user/project/merge_requests/test_coverage_visualization.html