--- /dev/null
+--- a/libc/sysdeps/linux/avr32/bits/atomic.h
++++ b/libc/sysdeps/linux/avr32/bits/atomic.h
+@@ -28,6 +28,7 @@ typedef uintmax_t uatomic_max_t;
+
+ #define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
+ ({ \
++ __uint32_t __result; \
+ __typeof__(*(mem)) __prev; \
+ __asm__ __volatile__( \
+ "/* __arch_compare_and_exchange_val_32_acq */\n" \