diff --git a/qemu/target/arm/helper.c b/qemu/target/arm/helper.c
index a1ef6a96..74fd5db4 100644
--- a/qemu/target/arm/helper.c
+++ b/qemu/target/arm/helper.c
@@ -5443,6 +5443,7 @@ void arm_v7m_cpu_do_interrupt(CPUState *cs)
     switch (cs->exception_index) {
     case EXCP_UDEF:
         //armv7m_nvic_set_pending(env->nvic, ARMV7M_EXCP_USAGE);
+        env->v7m.cfsr |= R_V7M_CFSR_UNDEFINSTR_MASK;
         return;
     case EXCP_SWI:
         /* The PC already points to the next instruction.  */