diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 5b09f52cc751dd3ffe9d6604db3fea986840ec11..29ce03f3175f43cd5a8baa599441b66097f55aa7 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -57,7 +57,7 @@ local-install-debian-job:   # This job runs in the test stage.
   script:
     # download zipped verapdf installer
     # HINT: https://software.verapdf.org/rel/1.24/verapdf-greenfield-1.24.1-installer.zip
-    - VERAPDF_VERSION_WITHOUT_PATCHLEVEL="$(echo ${VERAPDF_VERSION} | sed 's#^\([0-9]*\.[0-9]*\).*#\1#g')"
+    - VERAPDF_VERSION_WITHOUT_PATCHLEVEL="$(echo ${VERAPDF_VERSION} | sed "s#^\([0-9]*\.[0-9]*\).*#\1#g")"
     - ZIPPED_VERAPDF_INSTALLER_URL="https://software.verapdf.org/rel/${VERAPDF_VERSION_WITHOUT_PATCHLEVEL}/verapdf-greenfield-${VERAPDF_VERSION}-installer.zip"
     - wget "${ZIPPED_VERAPDF_INSTALLER_URL}"
     # unpack installer