diff --git a/vm_core.h b/vm_core.h
index 694fe2d2ca..ff5ff90a56 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -1407,7 +1407,7 @@ VALUE rb_binding_alloc(VALUE klass);
 
 /* for debug */
 extern void rb_vmdebug_stack_dump_raw(rb_thread_t *, rb_control_frame_t *);
-extern void rb_vmdebug_debug_print_pre(rb_thread_t *th, rb_control_frame_t *cfp, VALUE *_pc);
+extern void rb_vmdebug_debug_print_pre(rb_thread_t *th, rb_control_frame_t *cfp, const VALUE *_pc);
 extern void rb_vmdebug_debug_print_post(rb_thread_t *th, rb_control_frame_t *cfp);
 
 #define SDR() rb_vmdebug_stack_dump_raw(GET_THREAD(), GET_THREAD()->cfp)
diff --git a/vm_dump.c b/vm_dump.c
index 179c132a74..f843371390 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -336,7 +336,7 @@ rb_vmdebug_thread_dump_regs(VALUE thval)
 }
 
 void
-rb_vmdebug_debug_print_pre(rb_thread_t *th, rb_control_frame_t *cfp,VALUE *_pc)
+rb_vmdebug_debug_print_pre(rb_thread_t *th, rb_control_frame_t *cfp, const VALUE *_pc)
 {
     const rb_iseq_t *iseq = cfp->iseq;