1 files changed, 1 insertions, 1 deletions

diff --git a/src/WixToolset.Converters/ConverterExtensionCommandLine.cs b/src/WixToolset.Converters/ConverterExtensionCommandLine.cs
index 8d740a3a..06d3658c 100644
--- a/src/WixToolset.Converters/ConverterExtensionCommandLine.cs
+++ b/src/WixToolset.Converters/ConverterExtensionCommandLine.cs
@@ -21,7 +21,7 @@ namespace WixToolset.Converters
 
         private IServiceProvider ServiceProvider { get; }
 
-        public override IEnumerable<ExtensionCommandLineSwitch> CommandLineSwitches => new ExtensionCommandLineSwitch[]
+        public override IReadOnlyCollection<ExtensionCommandLineSwitch> CommandLineSwitches => new ExtensionCommandLineSwitch[]
         {
             new ExtensionCommandLineSwitch { Switch = "convert", Description = "Convert v3 source code to v4 source code." },
             new ExtensionCommandLineSwitch { Switch = "format", Description = "Ensures consistent formatting of source code." },