diff --git a/package/rt-tests/Config.in b/package/rt-tests/Config.in
index 47fa7cd840..8efa3d194e 100644
--- a/package/rt-tests/Config.in
+++ b/package/rt-tests/Config.in
@@ -1,5 +1,6 @@
 config BR2_PACKAGE_RT_TESTS
 	bool "rt-tests"
+	depends on BR2_TOOLCHAIN_HAS_SYNC_4 # __sync_*_4 intrisics
 	depends on BR2_TOOLCHAIN_HAS_THREADS_NPTL
 	depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_4_5
 	depends on BR2_USE_MMU # fork(), numactl
@@ -30,6 +31,7 @@ comment "rt-tests may not work on MIPS with an external uClibc toolchain"
 	depends on BR2_mips || BR2_mipsel || BR2_mips64 || BR2_mips64el
 
 comment "rt-tests needs a uClibc or glibc toolchain w/ NPTL, headers >= 4.5, dynamic library"
+	depends on BR2_TOOLCHAIN_HAS_SYNC_4
 	depends on !BR2_TOOLCHAIN_HAS_THREADS_NPTL || BR2_STATIC_LIBS \
 		|| BR2_TOOLCHAIN_USES_MUSL || !BR2_TOOLCHAIN_HEADERS_AT_LEAST_4_5
 	depends on BR2_USE_MMU