diff --git a/tests/amtest/src/tests/extintr.c b/tests/amtest/src/tests/extintr.c
index 4c304083d77b1c8bb6c92d83fa8eee6f3ed99d61..b6f2e3a9370a54d1e959920ff6cde786aacd15d7 100644
--- a/tests/amtest/src/tests/extintr.c
+++ b/tests/amtest/src/tests/extintr.c
@@ -188,6 +188,8 @@ void external_intr() {
   asm volatile("csrs sie, %0" : : "r"((1 << 9)));
   asm volatile("csrs sstatus, 2");
   plic_intr_init();
+  // enable WFI instruction
+  asm volatile("csrs 0x5c4, %0" : : "r"((0x7)));
 
   // trigger interrupts
   // s-mode