diff --git a/src/NzbDrone.Common.Test/Http/UserAgentParserFixture.cs b/src/NzbDrone.Common.Test/Http/UserAgentParserFixture.cs
new file mode 100644
index 000000000..e262a1466
--- /dev/null
+++ b/src/NzbDrone.Common.Test/Http/UserAgentParserFixture.cs
@@ -0,0 +1,24 @@
+using FluentAssertions;
+using NUnit.Framework;
+using NzbDrone.Common.Http;
+using NzbDrone.Test.Common;
+
+namespace NzbDrone.Common.Test.Http
+{
+    [TestFixture]
+    public class UserAgentParserFixture : TestBase
+    {
+        // Ref *Arr `_userAgent = $"{BuildInfo.AppName}/{BuildInfo.Version} ({osName} {osVersion})";`
+        // Ref Mylar `Mylar3/' +str(hash) +'(' +vers +') +http://www.github.com/mylar3/mylar3/`
+        [TestCase("Mylar3/ 3ee23rh23irqfq (13123123) http://www.github.com/mylar3/mylar3/", "Mylar3")]
+        [TestCase("Lidarr/1.0.0.2300 (ubuntu 20.04)", "Lidarr")]
+        [TestCase("Radarr/1.0.0.2300 (ubuntu 20.04)", "Radarr")]
+        [TestCase("Readarr/1.0.0.2300 (ubuntu 20.04)", "Readarr")]
+        [TestCase("Sonarr/3.0.6.9999 (ubuntu 20.04)", "Sonarr")]
+        [TestCase("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36", "Other")]
+        public void should_parse_user_agent(string userAgent, string parsedAgent)
+        {
+            UserAgentParser.ParseSource(userAgent).Should().Be(parsedAgent);
+        }
+    }
+}
diff --git a/src/NzbDrone.Common/Http/UserAgentParser.cs b/src/NzbDrone.Common/Http/UserAgentParser.cs
index e1164b9e8..8eb5f6d6a 100644
--- a/src/NzbDrone.Common/Http/UserAgentParser.cs
+++ b/src/NzbDrone.Common/Http/UserAgentParser.cs
@@ -9,7 +9,7 @@ namespace NzbDrone.Common.Http
 {
     public static class UserAgentParser
     {
-        private static readonly Regex AppSourceRegex = new Regex(@"(?<agent>.*)\/.*(\(.*\))?",
+        private static readonly Regex AppSourceRegex = new Regex(@"(?<agent>[a-z0-9]*)\/.*(?:\(.*\))?",
                                                         RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
         public static string SimplifyUserAgent(string userAgent)