diff --git a/gdb/unittests/parallel-for-selftests.c b/gdb/unittests/parallel-for-selftests.c
index a2cd47251eb..f149e72f0c7 100644
--- a/gdb/unittests/parallel-for-selftests.c
+++ b/gdb/unittests/parallel-for-selftests.c
@@ -20,10 +20,11 @@
 #include "defs.h"
 #include "gdbsupport/selftest.h"
 #include "gdbsupport/parallel-for.h"
-#include "gdbsupport/thread-pool.h"
 
 #if CXX_STD_THREAD
 
+#include "gdbsupport/thread-pool.h"
+
 namespace selftests {
 namespace parallel_for {