diff --git a/mrbgems/mruby-errno/src/errno.c b/mrbgems/mruby-errno/src/errno.c
index 11b050059..97132b4b5 100644
--- a/mrbgems/mruby-errno/src/errno.c
+++ b/mrbgems/mruby-errno/src/errno.c
@@ -275,12 +275,12 @@ static mrb_value
 mrb_sce_sys_fail(mrb_state *mrb, mrb_value cls)
 {
   struct RClass *sce;
-  mrb_value msg;
+  mrb_value msg, no;
   mrb_int argc;
 
   mrb->c->ci->mid = 0;
   sce = mrb_class_ptr(cls);
-  argc = mrb_get_args(mrb, "|S", &msg);
+  argc = mrb_get_args(mrb, "o|S", &no, &msg);
 
   struct RBasic* e = mrb_obj_alloc(mrb, MRB_TT_EXCEPTION, sce);
   mrb_value exc = mrb_obj_value(e);
@@ -288,7 +288,7 @@ mrb_sce_sys_fail(mrb_state *mrb, mrb_value cls)
     msg = mrb_nil_value();
   }
   exc = mrb_obj_value(e);
-  mrb_sce_init(mrb, exc, msg, mrb_fixnum_value(errno));
+  mrb_sce_init(mrb, exc, msg, no);
   mrb_exc_raise(mrb, exc);
   return mrb_nil_value();  /* NOTREACHED */
 }
@@ -301,7 +301,7 @@ mrb_mruby_errno_gem_init(mrb_state *mrb)
   ste = mrb->eStandardError_class;
 
   sce = mrb_define_class(mrb, "SystemCallError", ste);
-  mrb_define_class_method(mrb, sce, "_sys_fail", mrb_sce_sys_fail, MRB_ARGS_OPT(1));
+  mrb_define_class_method(mrb, sce, "_sys_fail", mrb_sce_sys_fail, MRB_ARGS_REQ(1));
   mrb_define_method(mrb, sce, "errno", mrb_sce_errno, MRB_ARGS_NONE());
   mrb_define_method(mrb, sce, "initialize", mrb_sce_init_m, MRB_ARGS_ARG(1, 1));
 
diff --git a/src/error.c b/src/error.c
index 0bea762eb..8773f1347 100644
--- a/src/error.c
+++ b/src/error.c
@@ -4,6 +4,7 @@
 ** See Copyright Notice in mruby.h
 */
 
+#include <errno.h>
 #include <stdlib.h>
 #include <mruby.h>
 #include <mruby/array.h>
@@ -511,14 +512,16 @@ MRB_API mrb_noreturn void
 mrb_sys_fail(mrb_state *mrb, const char *mesg)
 {
   struct RClass *sce;
+  mrb_int no;
 
+  no = (mrb_int)errno;
   if (mrb_class_defined_id(mrb, MRB_SYM(SystemCallError))) {
     sce = mrb_class_get_id(mrb, MRB_SYM(SystemCallError));
     if (mesg != NULL) {
-      mrb_funcall_id(mrb, mrb_obj_value(sce), MRB_SYM(_sys_fail), 1, mrb_str_new_cstr(mrb, mesg));
+      mrb_funcall_id(mrb, mrb_obj_value(sce), MRB_SYM(_sys_fail), 2, mrb_fixnum_value(no), mrb_str_new_cstr(mrb, mesg));
     }
     else {
-      mrb_funcall_id(mrb, mrb_obj_value(sce), MRB_SYM(_sys_fail), 0);
+      mrb_funcall_id(mrb, mrb_obj_value(sce), MRB_SYM(_sys_fail), 1, mrb_fixnum_value(no));
     }
   }