diff --git a/SMILEBASIC/compiler.d b/SMILEBASIC/compiler.d
index d1c849e..a862e33 100644
--- a/SMILEBASIC/compiler.d
+++ b/SMILEBASIC/compiler.d
@@ -126,6 +126,10 @@ class Function
         {
             //local変数をあたる
             //それでもだめならOPTION STRICTならエラー
+            if (c.isStrictMode)
+            {
+                throw new UndefinedVariable();
+            }
             this.variable[name] = VMVariable(var = ++variableIndex, c.getType(name));
         }
         return var;