diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 57b163651e..055687c0db 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -143,8 +143,7 @@ cache:
   fi
 
 .set_include_nightly_run: &set_include_nightly_run |
-  # in bash regex, (?:..) -> (..)
-  if [[ "$CI_MERGE_REQUEST_LABELS" =~ ^([^,\n\r]+,)*include_nightly_run(,[^,\n\r]+)*$ ]]; then
+  if echo "$CI_MERGE_REQUEST_LABELS" | egrep "^([^,\n\r]+,)*include_nightly_run(,[^,\n\r]+)*$"; then
     export INCLUDE_NIGHTLY_RUN="1"
   fi