diff --git a/src/Microsoft.AspNet.Identity.EntityFramework/project.json b/src/Microsoft.AspNet.Identity.EntityFramework/project.json
index 6e05ed07f6..36d274c109 100644
--- a/src/Microsoft.AspNet.Identity.EntityFramework/project.json
+++ b/src/Microsoft.AspNet.Identity.EntityFramework/project.json
@@ -12,6 +12,7 @@
   "frameworks": {
     "net451": {
       "frameworkAssemblies": {
+        "System.Runtime": "",
         "System.Threading.Tasks": ""
       }
     },