diff --git a/src/BirdsiteLive.Common/Regexes/UserRegex.cs b/src/BirdsiteLive.Common/Regexes/UserRegex.cs
new file mode 100644
index 0000000..b3da74a
--- /dev/null
+++ b/src/BirdsiteLive.Common/Regexes/UserRegex.cs
@@ -0,0 +1,9 @@
+using System.Text.RegularExpressions;
+
+namespace BirdsiteLive.Common.Regexes
+{
+    public class UserRegex
+    {
+        public static readonly Regex TwitterAccountRegex = new Regex(@"^[a-zA-Z0-9_]+$");
+    }
+}
\ No newline at end of file
diff --git a/src/BirdsiteLive/Controllers/UsersController.cs b/src/BirdsiteLive/Controllers/UsersController.cs
index a22ae73..486d9b6 100644
--- a/src/BirdsiteLive/Controllers/UsersController.cs
+++ b/src/BirdsiteLive/Controllers/UsersController.cs
@@ -9,6 +9,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using BirdsiteLive.ActivityPub;
 using BirdsiteLive.ActivityPub.Models;
+using BirdsiteLive.Common.Regexes;
 using BirdsiteLive.Common.Settings;
 using BirdsiteLive.Domain;
 using BirdsiteLive.Models;
@@ -28,7 +29,6 @@ namespace BirdsiteLive.Controllers
         private readonly IUserService _userService;
         private readonly IStatusService _statusService;
         private readonly InstanceSettings _instanceSettings;
-        private readonly Regex _twitterAccountRegex = new Regex(@"^[a-zA-Z0-9_]+$");
 
         #region Ctor
         public UsersController(ITwitterUserService twitterUserService, IUserService userService, IStatusService statusService, InstanceSettings instanceSettings, ITwitterTweetsService twitterTweetService)
@@ -62,7 +62,7 @@ namespace BirdsiteLive.Controllers
             // Ensure valid username 
             // https://help.twitter.com/en/managing-your-account/twitter-username-rules
             TwitterUser user = null;
-            if (!string.IsNullOrWhiteSpace(id) && _twitterAccountRegex.IsMatch(id) && id.Length <= 15)
+            if (!string.IsNullOrWhiteSpace(id) && UserRegex.TwitterAccountRegex.IsMatch(id) && id.Length <= 15)
                 user = _twitterUserService.GetUser(id);
 
             var acceptHeaders = Request.Headers["Accept"];
diff --git a/src/BirdsiteLive/Controllers/WellKnownController.cs b/src/BirdsiteLive/Controllers/WellKnownController.cs
index 3f060a7..f974665 100644
--- a/src/BirdsiteLive/Controllers/WellKnownController.cs
+++ b/src/BirdsiteLive/Controllers/WellKnownController.cs
@@ -4,6 +4,7 @@ using System.Linq;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using BirdsiteLive.ActivityPub.Converters;
+using BirdsiteLive.Common.Regexes;
 using BirdsiteLive.Common.Settings;
 using BirdsiteLive.DAL.Contracts;
 using BirdsiteLive.Models;
@@ -20,7 +21,6 @@ namespace BirdsiteLive.Controllers
         private readonly ITwitterUserService _twitterUserService;
         private readonly ITwitterUserDal _twitterUserDal;
         private readonly InstanceSettings _settings;
-        private readonly Regex _twitterAccountRegex = new Regex(@"^[a-zA-Z0-9_]+$");
 
         #region Ctor
         public WellKnownController(InstanceSettings settings, ITwitterUserService twitterUserService, ITwitterUserDal twitterUserDal)
@@ -164,7 +164,7 @@ namespace BirdsiteLive.Controllers
 
             // Ensure valid username 
             // https://help.twitter.com/en/managing-your-account/twitter-username-rules
-            if (string.IsNullOrWhiteSpace(name) || !_twitterAccountRegex.IsMatch(name) || name.Length > 15 )
+            if (string.IsNullOrWhiteSpace(name) || !UserRegex.TwitterAccountRegex.IsMatch(name) || name.Length > 15 )
                 return NotFound();
 
             if (!string.IsNullOrWhiteSpace(domain) && domain != _settings.Domain)