diff --git a/vm_exec.c b/vm_exec.c
--- a/vm_exec.c
+++ b/vm_exec.c
@@ -49,6 +49,7 @@
 #endif
 #endif
 
+#if 0
 #if __GNUC__ && __i386__
     DECL_SC_REG(VALUE *, pc, "di");
     DECL_SC_REG(rb_control_frame_t *, cfp, "si");
@@ -59,6 +60,7 @@
     DECL_SC_REG(rb_control_frame_t *, cfp, "15");
 #define USE_MACHINE_REGS 1
 
+#endif
 #else
     register rb_control_frame_t *reg_cfp;
     VALUE *reg_pc;