diff --git a/.kokoro/build.sh b/.kokoro/build.sh
index 9b2c3b0240aa..3b9dcfab010a 100755
--- a/.kokoro/build.sh
+++ b/.kokoro/build.sh
@@ -65,7 +65,7 @@ case ${JOB_TYPE} in
     fi
     ;;
   graalvm-presubmit)
-    if [ -n "${MAVEN_MODULES}" ]; then
+    if [ -z "${MAVEN_MODULES}" ]; then
       echo "MAVEN_MODULES not defined in environment."
       exit 1
     fi