diff --git a/tests/ExtraTests/CMakeLists.txt b/tests/ExtraTests/CMakeLists.txt
index 281a04fa..6aafd527 100644
--- a/tests/ExtraTests/CMakeLists.txt
+++ b/tests/ExtraTests/CMakeLists.txt
@@ -565,4 +565,5 @@ add_test(NAME ThreadSafetyTests
 set_tests_properties(ThreadSafetyTests
   PROPERTIES
     PASS_REGULAR_EXPRESSION "assertions: 8001 | 4000 passed | 4001 failed"
+    RUN_SERIAL ON
 )
diff --git a/tests/ExtraTests/X94-ThreadSafetyTests.cpp b/tests/ExtraTests/X94-ThreadSafetyTests.cpp
index 70e6dc66..b0ad38d9 100644
--- a/tests/ExtraTests/X94-ThreadSafetyTests.cpp
+++ b/tests/ExtraTests/X94-ThreadSafetyTests.cpp
@@ -27,9 +27,9 @@ TEST_CASE( "Failed REQUIRE in the main thread is fine" ) {
     std::vector<std::thread> threads;
     for ( size_t t = 0; t < 4; ++t) {
         threads.emplace_back( [t]() {
-//            CAPTURE(t);
+            CAPTURE(t);
             for (size_t i = 0; i < 1'000; ++i) {
-//                CAPTURE(i);
+                CAPTURE(i);
                 CHECK( false );
                 CHECK( true );
             }