diff --git a/actionpack/lib/action_dispatch/http/cache.rb b/actionpack/lib/action_dispatch/http/cache.rb
index 9b9e81440b35e1419f5706f21858b7cbd743d974..e9fdf75cc8414285e79cf89f30b19481de5b3ae5 100644
--- a/actionpack/lib/action_dispatch/http/cache.rb
+++ b/actionpack/lib/action_dispatch/http/cache.rb
@@ -89,7 +89,7 @@ def handle_conditional_get!
           if etag? || last_modified? || !@cache_control.empty?
             set_conditional_cache_control!
           elsif nonempty_ok_response?
-            self.etag = @body
+            self.etag = body
 
             if request && request.etag_matches?(etag)
               self.status = 304
@@ -137,4 +137,4 @@ def set_conditional_cache_control!
       end
     end
   end
-end
\ No newline at end of file
+end