diff --git a/.gitlab/ci/configure_macos_x86_64_xcode.cmake b/.gitlab/ci/configure_macos_x86_64_xcode.cmake
index 1b976d261a..f1b91ec9a3 100644
--- a/.gitlab/ci/configure_macos_x86_64_xcode.cmake
+++ b/.gitlab/ci/configure_macos_x86_64_xcode.cmake
@@ -1,2 +1,3 @@
+set(CMake_TEST_RunCMake_ExternalProject_RUN_SERIAL ON CACHE BOOL "")
 include("${CMAKE_CURRENT_LIST_DIR}/configure_macos_common.cmake")
 include("${CMAKE_CURRENT_LIST_DIR}/configure_external_test.cmake")