diff --git a/src/Microsoft.AspNetCore.Identity/project.json b/src/Microsoft.AspNetCore.Identity/project.json
index e6a4bcbd12..8bc53893be 100644
--- a/src/Microsoft.AspNetCore.Identity/project.json
+++ b/src/Microsoft.AspNetCore.Identity/project.json
@@ -21,7 +21,9 @@
   "frameworks": {
     "net451": {},
     "netstandard1.3": {
-      "dependencies": {},
+      "dependencies": {
+        "System.Text.RegularExpressions": "4.0.12-*"
+      },
       "imports": [
         "dotnet5.4",
         "portable-net451+win8"