diff --git a/actionpack/lib/action_dispatch/http/cache.rb b/actionpack/lib/action_dispatch/http/cache.rb
index cc1cb3f0f03045e7be38e20707f4d30f1292a711..be87343b20d9e5f101a20fa6cff752b3e8098d25 100644
--- a/actionpack/lib/action_dispatch/http/cache.rb
+++ b/actionpack/lib/action_dispatch/http/cache.rb
@@ -8,13 +8,13 @@ module Request
         HTTP_IF_NONE_MATCH     = 'HTTP_IF_NONE_MATCH'.freeze
 
         def if_modified_since
-          if since = env[HTTP_IF_MODIFIED_SINCE]
+          if since = get_header(HTTP_IF_MODIFIED_SINCE)
             Time.rfc2822(since) rescue nil
           end
         end
 
         def if_none_match
-          env[HTTP_IF_NONE_MATCH]
+          get_header HTTP_IF_NONE_MATCH
         end
 
         def if_none_match_etags