diff --git a/src/NexusMods.Telemetry/EventDefinition.cs b/src/NexusMods.Telemetry/EventDefinition.cs
index fed9432a7..56c879fcf 100644
--- a/src/NexusMods.Telemetry/EventDefinition.cs
+++ b/src/NexusMods.Telemetry/EventDefinition.cs
@@ -1,3 +1,5 @@
+using System.Net;
+using System.Text;
 using JetBrains.Annotations;
 
 namespace NexusMods.Telemetry;
@@ -8,4 +10,14 @@ namespace NexusMods.Telemetry;
 /// <param name="Category">The event category</param>
 /// <param name="Action">The event action</param>
 [PublicAPI]
-public record EventDefinition(string Category, string Action);
+public record EventDefinition(string Category, string Action)
+{
+    internal byte[] SafeCategory { get; } = Encode(Category);
+    internal byte[] SafeAction { get; } = Encode(Action);
+
+    private static byte[] Encode(string value)
+    {
+        var bytes = Encoding.UTF8.GetBytes(value);
+        return WebUtility.UrlEncodeToBytes(bytes, offset: 0, count: bytes.Length);
+    }
+};
diff --git a/src/NexusMods.Telemetry/EventMetadata.cs b/src/NexusMods.Telemetry/EventMetadata.cs
index c680d1dd4..ec2246dab 100644
--- a/src/NexusMods.Telemetry/EventMetadata.cs
+++ b/src/NexusMods.Telemetry/EventMetadata.cs
@@ -1,4 +1,6 @@
 using System.Diagnostics;
+using System.Net;
+using System.Text;
 using JetBrains.Annotations;
 
 namespace NexusMods.Telemetry;
@@ -41,4 +43,12 @@ public EventMetadata(string? name, TimeProvider? timeProvider = null)
     /// Checks whether the struct wasn't default initialized.
     /// </summary>
     public bool IsValid() => Name is not null || CurrentTime != default(TimeOnly);
+
+    internal byte[] SafeName => Name is null ? [] : Encode(Name);
+
+    private static byte[] Encode(string value)
+    {
+        var bytes = Encoding.UTF8.GetBytes(value);
+        return WebUtility.UrlEncodeToBytes(bytes, offset: 0, count: bytes.Length);
+    }
 }
diff --git a/src/NexusMods.Telemetry/EventSender.cs b/src/NexusMods.Telemetry/EventSender.cs
index a29bd12a5..3ffbf1065 100644
--- a/src/NexusMods.Telemetry/EventSender.cs
+++ b/src/NexusMods.Telemetry/EventSender.cs
@@ -163,14 +163,29 @@ private static void SerializeEvent(IBufferWriter<byte> writer, ValueTuple<EventD
         }
 
         sb.Append("&e_c="); // Event category
-        sb.Append(definition.Category);
+        {
+            var input = definition.SafeCategory.AsSpan();
+            var destination = sb.GetSpan(sizeHint: input.Length);
+            input.CopyTo(destination);
+            sb.Advance(input.Length);
+        }
+
         sb.Append("&e_a="); // Event action
-        sb.Append(definition.Action);
+        {
+            var input = definition.SafeAction.AsSpan();
+            var destination = sb.GetSpan(sizeHint: input.Length);
+            input.CopyTo(destination);
+            sb.Advance(input.Length);
+
+        }
 
         if (metadata.Name is not null)
         {
             sb.Append("&e_n="); // Event name
-            sb.Append(metadata.Name);
+            var input = metadata.SafeName.AsSpan();
+            var destination = sb.GetSpan(sizeHint: input.Length);
+            input.CopyTo(destination);
+            sb.Advance(input.Length);
         }
 
         sb.Append("&h="); // The current hour (local time)
diff --git a/tests/NexusMods.Telemetry.Tests/EventSenderTests.cs b/tests/NexusMods.Telemetry.Tests/EventSenderTests.cs
index 90e932c3e..d03eb03f8 100644
--- a/tests/NexusMods.Telemetry.Tests/EventSenderTests.cs
+++ b/tests/NexusMods.Telemetry.Tests/EventSenderTests.cs
@@ -41,16 +41,16 @@ public async Task Test()
                 using var stream = content!.ReadAsStream();
                 using var textReader = new StreamReader(stream, Encoding.UTF8);
                 var res = textReader.ReadToEnd();
-                ExpectJson("""{ "requests": ["?idsite=7&rec=1&apiv=1&send_image=0&ca=1&uid=1337&e_c=Game&e_a=Add Game&e_n=stardewvalley&h=0&m=0&s=0","?idsite=7&rec=1&apiv=1&send_image=0&ca=1&uid=1337&e_c=Loadout&e_a=Create Loadout&e_n=stardewvalley&h=0&m=0&s=1"] }""", res);
+                ExpectJson("""{ "requests": ["?idsite=7&rec=1&apiv=1&send_image=0&ca=1&uid=1337&e_c=Game&e_a=Add+Game&e_n=Mount+%26+Blade&h=0&m=0&s=0","?idsite=7&rec=1&apiv=1&send_image=0&ca=1&uid=1337&e_c=Loadout&e_a=Create+Loadout&e_n=Mount+%26+Blade&h=0&m=0&s=1"] }""", res);
             });
 
         var sender = new EventSender(loginManager, new HttpClient(messageHandler));
 
         var timeProvider = new FakeTimeProvider();
-        sender.AddEvent(definition: Events.Game.AddGame, metadata: new EventMetadata(name: "stardewvalley", timeProvider: timeProvider));
+        sender.AddEvent(definition: Events.Game.AddGame, metadata: new EventMetadata(name: "Mount & Blade", timeProvider: timeProvider));
 
         timeProvider.Advance(delta: TimeSpan.FromSeconds(1));
-        sender.AddEvent(definition: Events.Loadout.CreateLoadout, metadata: new EventMetadata(name: "stardewvalley", timeProvider: timeProvider));
+        sender.AddEvent(definition: Events.Loadout.CreateLoadout, metadata: new EventMetadata(name: "Mount & Blade", timeProvider: timeProvider));
 
         await sender.Run();
     }