diff --git a/run-make-check.sh b/run-make-check.sh
index 59866ecec63f9..6e032e9f1ef7a 100755
--- a/run-make-check.sh
+++ b/run-make-check.sh
@@ -59,7 +59,7 @@ function main() {
         cmake_opts+=" -DWITH_SEASTAR=ON"
     fi
     if [ $WITH_ZBD ]; then
-        cmake_opts += " -DWITH_ZBD=ON"
+        cmake_opts+=" -DWITH_ZBD=ON"
     fi
     configure $cmake_opts $@
     build tests && echo "make check: successful build on $(git rev-parse HEAD)"