diff --git a/M6502/ProfileEventArgs.cs b/M6502/ProfileEventArgs.cs
index 5dafc15..28dbab6 100644
--- a/M6502/ProfileEventArgs.cs
+++ b/M6502/ProfileEventArgs.cs
@@ -1,6 +1,6 @@
 namespace EightBit
 {
-    public class ProfileEventArgs(string output) : EventArgs
+    public sealed class ProfileEventArgs(string output) : EventArgs
     {
         public string Output { get; } = output;
     }
diff --git a/M6502/ProfileInstructionEventArgs.cs b/M6502/ProfileInstructionEventArgs.cs
index adb4716..4517db5 100644
--- a/M6502/ProfileInstructionEventArgs.cs
+++ b/M6502/ProfileInstructionEventArgs.cs
@@ -1,6 +1,6 @@
 namespace EightBit
 {
-    public class ProfileInstructionEventArgs(byte instruction, long cycles, long count) : EventArgs
+    public sealed class ProfileInstructionEventArgs(byte instruction, long cycles, long count) : EventArgs
     {
         public byte Instruction { get; } = instruction;
 
diff --git a/M6502/ProfileLineEventArgs.cs b/M6502/ProfileLineEventArgs.cs
index ae7e2b8..d9b6c3a 100644
--- a/M6502/ProfileLineEventArgs.cs
+++ b/M6502/ProfileLineEventArgs.cs
@@ -1,6 +1,6 @@
 namespace EightBit
 {
-    public class ProfileLineEventArgs(ushort address, string source, long cycles, long count, Dictionary<int, long> cycleDistributions) : CycleCountedEventArgs(cycles, count)
+    public sealed class ProfileLineEventArgs(ushort address, string source, long cycles, long count, Dictionary<int, long> cycleDistributions) : CycleCountedEventArgs(cycles, count)
     {
         public ushort Address { get; } = address;
 
diff --git a/M6502/ProfileScopeEventArgs.cs b/M6502/ProfileScopeEventArgs.cs
index b155e84..d75ab33 100644
--- a/M6502/ProfileScopeEventArgs.cs
+++ b/M6502/ProfileScopeEventArgs.cs
@@ -1,6 +1,6 @@
 namespace EightBit
 {
-    public class ProfileScopeEventArgs(int id, long cycles, long count) : CycleCountedEventArgs(cycles, count)
+    public sealed class ProfileScopeEventArgs(int id, long cycles, long count) : CycleCountedEventArgs(cycles, count)
     {
         public int ID { get; } = id;
     }