diff --git a/lib/simple_redis_cache.rb b/lib/simple_redis_cache.rb
index 5ecdd23..547532b 100644
--- a/lib/simple_redis_cache.rb
+++ b/lib/simple_redis_cache.rb
@@ -10,14 +10,11 @@ def redis
     @redis ||= Redis.new
   end
 
-  def cache(*args, &block)
-    redis[args.first]=(block ? block.call : args.last)
+  def cache(key, opts={}, &block)
+    unless redis.exists(key)
+      redis[key]=block.call
+      redis.expire(key, opts[:ttl]) if opts[:ttl]
+    end
   end
 
-  def get(key)
-    redis[key]
-  end
-
-
-
 end
diff --git a/test/simple_redis_cache_test.rb b/test/simple_redis_cache_test.rb
index 9a2905a..70a1f29 100755
--- a/test/simple_redis_cache_test.rb
+++ b/test/simple_redis_cache_test.rb
@@ -10,21 +10,23 @@ def setup
     redis.flushdb
   end
 
-  # Called after every test method runs. Can be used to tear
-  # down fixture information.
 
-  def teardown
-    # Do nothing
-  end
 
-  def test_cache_object
-    cache('hello', 'world')
-    assert_equal(get('hello'), 'world')
+  def test_expire_block
+    cache('hello', :ttl=>1){ 'world' }
+    sleep(2)
+    assert_nil(redis['hello'])
   end
 
-  def test_cache_block
+  def test_cache
     cache('hello'){ 'world' }
-    assert_equal(get('hello'), 'world')
+    assert_equal(redis['hello'], 'world')
+  end
+
+  def test_block_is_only_executed_once
+    @index = 0
+    2.times{ cache('hello'){ @index+=1 } }
+    assert_equal(@index, 1)
   end