diff --git a/ci/common/build.bash b/ci/common/build.bash
index ab713b3..61b3654 100755
--- a/ci/common/build.bash
+++ b/ci/common/build.bash
@@ -210,7 +210,7 @@ log "Test..."
   # Make sure test_status captures ctest, not tee:
   # https://stackoverflow.com/a/999259/11130318
   set -o pipefail
-  echo_and_run_timed "Test" ctest ${CTEST_FLAGS} | tee ctest_log
+  echo_and_run_timed "Test" ctest ${CTEST_FLAGS} -j ${PARALLEL_LEVEL} | tee ctest_log
 )
 
 test_status=$?