diff --git a/build.sh b/build.sh
index df5e54c..1322a7a 100755
--- a/build.sh
+++ b/build.sh
@@ -16,7 +16,7 @@
 # License along with this library; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 
-if [[ -v CI ]]
+if [ -z "$CI" ]
 then
 	DOCKER_INTERACTIVE_OPTS=""
 else