diff --git a/libc/arch-arm/bionic/atomics_arm.S b/libc/arch-arm/bionic/atomics_arm.S
index f2e369d..7818228 100644
--- a/libc/arch-arm/bionic/atomics_arm.S
+++ b/libc/arch-arm/bionic/atomics_arm.S
@@ -26,6 +26,7 @@
  * SUCH DAMAGE.
  */
 #include <sys/linux-syscalls.h>
+#include <machine/cpu-features.h>
 
 .global __atomic_cmpxchg
 .type __atomic_cmpxchg, %function