diff --git a/Makefile b/Makefile
index 99d8dfc..9ac5771 100644
--- a/Makefile
+++ b/Makefile
@@ -12,6 +12,7 @@ LDFLAGS = -Tkernel.ld
 LDFLAGS += -m elf64lriscv
 
 CFLAGS = -Wall -Werror -O
+CFLAGS += -Wno-unused-result
 CFLAGS += -mcmodel=medany
 CFLAGS += -march=rv64gc -mabi=lp64
 CFLAGS += -ffreestanding -fno-common -nostdlib -mno-relax
diff --git a/kern/ispinlock.c b/kern/ispinlock.c
index e2a9e79..4a7b751 100644
--- a/kern/ispinlock.c
+++ b/kern/ispinlock.c
@@ -4,7 +4,7 @@ void spinlock_init(spinlock_t *l) {
     l->v = 0;
 }
 
-bool spin_trylock(spinlock_t *l) {
+__attribute__((warn_unused_result)) bool spin_trylock(spinlock_t *l) {
     uint32_t old;
     // old = xchg_acquire(&l->v, 1) using AMO
     __asm__ volatile("amoswap.w.aq %0, %2, (%1)\n" : "=&r"(old) : "r"(&l->v), "r"(1u) : "memory");