diff --git a/test/Microsoft.AspNetCore.Hosting.Tests/project.json b/test/Microsoft.AspNetCore.Hosting.Tests/project.json
index 0c155b27cd..17a1672d38 100644
--- a/test/Microsoft.AspNetCore.Hosting.Tests/project.json
+++ b/test/Microsoft.AspNetCore.Hosting.Tests/project.json
@@ -17,6 +17,10 @@
   },
   "frameworks": {
     "dnx451": {
+      "frameworkAssemblies":
+      {
+        "System.Threading.Tasks": ""
+      },
       "dependencies": {
         "xunit.runner.console": "2.1.0"
       }
diff --git a/test/Microsoft.AspNetCore.TestHost.Tests/project.json b/test/Microsoft.AspNetCore.TestHost.Tests/project.json
index 2b0035dbdc..52747457b9 100644
--- a/test/Microsoft.AspNetCore.TestHost.Tests/project.json
+++ b/test/Microsoft.AspNetCore.TestHost.Tests/project.json
@@ -12,6 +12,10 @@
   },
   "frameworks": {
     "dnx451": {
+      "frameworkAssemblies":
+      {
+        "System.Threading.Tasks": ""
+      },
       "dependencies": {
         "xunit.runner.console": "2.1.0"
       }