diff --git a/.vs/ACME.net/v14/.suo b/.vs/ACME.net/v14/.suo
index f64056c..d41d029 100644
Binary files a/.vs/ACME.net/v14/.suo and b/.vs/ACME.net/v14/.suo differ
diff --git a/global.json b/global.json
index 82ac346..4497ad7 100644
--- a/global.json
+++ b/global.json
@@ -2,7 +2,7 @@
     "projects": [ "src", "test" ],
     "sdk": {
       "version": "1.0.0-rc1-final",
-        "runtime": "coreclr",
+        "runtime": "clr",
         "architecture": "x64"
     }
 }
diff --git a/src/Oocx.ACME.Console/AcmeProcess.cs b/src/Oocx.ACME.Console/AcmeProcess.cs
index 572b92f..80d4eb5 100644
--- a/src/Oocx.ACME.Console/AcmeProcess.cs
+++ b/src/Oocx.ACME.Console/AcmeProcess.cs
@@ -164,7 +164,7 @@ private async Task<bool> AuthorizeForDomain(string domain)
 
         private async Task RegisterWithServer()
         {
-            var registration = await client.RegisterAsync(options.AcceptTermsOfService ? options.TermsOfServiceUri : null, options.Contact);
+            var registration = await client.RegisterAsync(options.AcceptTermsOfService ? options.TermsOfServiceUri : null, new[] {options.Contact});
             Info($"Terms of service: {registration.Agreement}");
             Verbose($"Created at: {registration.CreatedAt}");
             Verbose($"Id: {registration.Id}");
@@ -179,7 +179,7 @@ private async Task RegisterWithServer()
                     Error($"Cannot accept terms of service. The terms of service uri is '{registration.Agreement}', expected it to be '{options.TermsOfServiceUri}'.");
                     return;
                 }
-                await client.UpdateRegistrationAsync(registration.Location, registration.Agreement, options.Contact);                
+                await client.UpdateRegistrationAsync(registration.Location, registration.Agreement, new[] {options.Contact});                
             }
         }
 
diff --git a/src/Oocx.ACME.Console/Options.cs b/src/Oocx.ACME.Console/Options.cs
index 465893d..485bf17 100644
--- a/src/Oocx.ACME.Console/Options.cs
+++ b/src/Oocx.ACME.Console/Options.cs
@@ -48,6 +48,6 @@ public class Options
         public string IISBinidng { get; set; }
 
         [Option('m', "contact", HelpText = "The contact information for the registration request. Example: mailto:you@example.com")]
-        public string[] Contact { get; set; }
+        public string Contact { get; set; }
     }    
 }
\ No newline at end of file