diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 4645d8363c..78cd3750c7 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -748,7 +748,7 @@ cross-version-config-tests:
     # Run the setup phase of all system tests in the most recently tagged BIND 9
     # release using the binaries built for the current BIND 9 version.  This
     # intends to detect obvious backward compatibility issues with the latter.
-    - sed -i -E "s|(export TOP_BUILDDIR)=.*|\1=${CI_PROJECT_DIR}|" conf.sh
+    - sed -i "s|export \(.*\)=\$TOP_BUILDDIR|export \1=\$CI_PROJECT_DIR|" conf.sh
     - >
       "$PYTEST" --setup-only --junit-xml="$CI_PROJECT_DIR"/junit.xml -n "${TEST_PARALLEL_JOBS:-1}"
   needs: