diff --git a/target/lm32/op_helper.c b/target/lm32/op_helper.c
index 577f830..234d55e 100644
--- a/target/lm32/op_helper.c
+++ b/target/lm32/op_helper.c
@@ -102,12 +102,16 @@
 
 void HELPER(wcsr_im)(CPULM32State *env, uint32_t im)
 {
+    qemu_mutex_lock_iothread();
     lm32_pic_set_im(env->pic_state, im);
+    qemu_mutex_unlock_iothread();
 }
 
 void HELPER(wcsr_ip)(CPULM32State *env, uint32_t im)
 {
+    qemu_mutex_lock_iothread();
     lm32_pic_set_ip(env->pic_state, im);
+    qemu_mutex_unlock_iothread();
 }
 
 void HELPER(wcsr_jtx)(CPULM32State *env, uint32_t jtx)