diff --git a/src/vm.c b/src/vm.c
index 489b9d1a3..99dc1bb5a 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -336,19 +336,21 @@ cipush(mrb_state *mrb, mrb_int push_stacks, uint8_t cci, struct RClass *target_c
        const struct RProc *proc, struct RProc *blk, mrb_sym mid, uint16_t argc)
 {
   struct mrb_context *c = mrb->c;
-  mrb_callinfo *ci = c->ci;
+  mrb_callinfo *ci = c->ci + 1;
 
-  if (ci + 1 == c->ciend) {
+  if (ci < c->ciend) {
+    c->ci = ci;
+  }
+  else {
     ptrdiff_t size = ci - c->cibase;
 
-    if (size > MRB_CALL_LEVEL_MAX) {
+    if (size >= MRB_CALL_LEVEL_MAX) {
       mrb_exc_raise(mrb, mrb_obj_value(mrb->stack_err));
     }
     c->cibase = (mrb_callinfo*)mrb_realloc(mrb, c->cibase, sizeof(mrb_callinfo)*size*2);
-    c->ci = c->cibase + size;
+    c->ci = ci = c->cibase + size;
     c->ciend = c->cibase + size * 2;
   }
-  ci = ++c->ci;
   ci->mid = mid;
   CI_PROC_SET(ci, proc);
   ci->blk = blk;