diff --git a/test/system/services/thread-test/build.zig b/test/system/services/thread-test/build.zig
index ba0ffe1..ce33224 100644
--- a/test/system/services/thread-test/build.zig
+++ b/test/system/services/thread-test/build.zig
@@ -11,6 +11,7 @@ pub fn build(b: *std.Build) void {
         .name = "thread-test",
         .root_source_file = b.path("thread-test.zig"),
         .domains = build_support.domains(b),
+        .threaded = true, // real atomics/TLS (docs/threading.md)
     });
     b.installArtifact(exe);
 }