1 files changed, 5 insertions, 6 deletions
diff --git a/src/kernel.c b/src/kernel.c
index cb938f152..485485da5 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -189,12 +189,11 @@ mrb_f_block_given_p_m(mrb_state *mrb, mrb_value self)
     if (ci->proc->env && ci->proc->env->stack) {
       mrb_value *sp = ci->proc->env->stack;
 
-      while (mrb->c->cibase < ci) {
-        if (ci->stackent == sp) {
-          break;
-        }
-        ci--;
-      }
+      /* top-level does not have block slot (alway false) */
+      if (sp == mrb->c->stbase)
+        return mrb_false_value();
+      ci = mrb->c->cibase + ci->proc->env->cioff;
+      bp = ci[1].stackent + 1;
     }
     if (ci->argc > 0) {
       bp += ci->argc;