diff --git a/src/unix/async.c b/src/unix/async.c
index d813db46c..f7995fc35 100644
--- a/src/unix/async.c
+++ b/src/unix/async.c
@@ -415,6 +415,6 @@ static void uv__cpu_relax(void) {
 #elif !defined(__APPLE__) && (defined(__powerpc64__) || defined(__ppc64__) || defined(__PPC64__))
   __asm__ __volatile__ ("or 1,1,1; or 2,2,2" ::: "memory");
 #elif defined(__riscv) && __riscv_xlen == 64
-  __asm__ volatile(".insn 0x0100000f" ::: "memory");
+  __asm__ volatile(".insn 0x0100000f" ::: "memory");  /* FENCE */
 #endif
 }