diff --git a/lib/erb.rb b/lib/erb.rb
index a950aec..cac05f0 100644
--- a/lib/erb.rb
+++ b/lib/erb.rb
@@ -890,10 +890,26 @@ def result(b=new_toplevel)
   # by a Hash object.
   def result_with_hash(hash)
     b = new_toplevel
+    
+    backup = {}
+    news = []
     hash.each_pair do |key, value|
+        if b.local_variable_defined?(key)
+          backup[key] = b.local_variable_get(key)
+        else
+          news << key
+        end
+        b.local_variable_set(key, value)
+    end
+
+    ret = result(b)
+
+    backup.each_pair do |key, value|
       b.local_variable_set(key, value)
     end
-    result(b)
+    news.each { |key| b.local_variable_set(key, nil) }
+
+    ret
   end
 
   ##