3 files changed, 12 insertions, 8 deletions

diff --git a/src/WixToolset.Core/CommandLine/BuildCommand.cs b/src/WixToolset.Core/CommandLine/BuildCommand.cs
index fed95958..065467bd 100644
--- a/src/WixToolset.Core/CommandLine/BuildCommand.cs
+++ b/src/WixToolset.Core/CommandLine/BuildCommand.cs
@@ -841,8 +841,7 @@ namespace WixToolset.Core.CommandLine
                 }
                 else
                 {
-                    this.Messaging.Write(ErrorMessages.IllegalSuppressWarningId(paramArg));
-                    parser.ErrorArgument = parameter;
+                    parser.ReportErrorArgument(parameter, ErrorMessages.IllegalSuppressWarningId(paramArg));
                 }
             }
 
@@ -859,8 +858,7 @@ namespace WixToolset.Core.CommandLine
                 }
                 else
                 {
-                    this.Messaging.Write(ErrorMessages.IllegalSuppressWarningId(paramArg));
-                    parser.ErrorArgument = parameter;
+                    parser.ReportErrorArgument(parameter, ErrorMessages.IllegalSuppressWarningId(paramArg));
                 }
             }
         }
diff --git a/src/WixToolset.Core/CommandLine/CommandLine.cs b/src/WixToolset.Core/CommandLine/CommandLine.cs
index 5439eb39..0c21eaaa 100644
--- a/src/WixToolset.Core/CommandLine/CommandLine.cs
+++ b/src/WixToolset.Core/CommandLine/CommandLine.cs
@@ -97,19 +97,19 @@ namespace WixToolset.Core.CommandLine
                 {
                     if (!this.TryParseCommand(arg, parser, extensions, out command))
                     {
-                        parser.ErrorArgument = arg;
+                        parser.ReportErrorArgument(arg);
                     }
                 }
                 else if (parser.IsSwitch(arg))
                 {
                     if (!command.TryParseArgument(parser, arg) && !TryParseCommandLineArgumentWithExtension(arg, parser, extensions))
                     {
-                        parser.ErrorArgument = arg;
+                        parser.ReportErrorArgument(arg);
                     }
                 }
                 else if (!TryParseCommandLineArgumentWithExtension(arg, parser, extensions) && !command.TryParseArgument(parser, arg))
                 {
-                    parser.ErrorArgument = arg;
+                    parser.ReportErrorArgument(arg);
                 }
             }
 
diff --git a/src/WixToolset.Core/CommandLine/CommandLineParser.cs b/src/WixToolset.Core/CommandLine/CommandLineParser.cs
index e78da47e..015d3e62 100644
--- a/src/WixToolset.Core/CommandLine/CommandLineParser.cs
+++ b/src/WixToolset.Core/CommandLine/CommandLineParser.cs
@@ -12,7 +12,7 @@ namespace WixToolset.Core.CommandLine
     {
         private const string ExpectedArgument = "expected argument";
 
-        public string ErrorArgument { get; set; }
+        public string ErrorArgument { get; private set; }
 
         private Queue<string> RemainingArguments { get; }
 
@@ -122,6 +122,12 @@ namespace WixToolset.Core.CommandLine
             return false;
         }
 
+        public void ReportErrorArgument(string argument, Message message = null)
+        {
+            this.Messaging.Write(message ?? ErrorMessages.AdditionalArgumentUnexpected(argument));
+            this.ErrorArgument = argument;
+        }
+
         public bool TryGetNextSwitchOrArgument(out string arg)
         {
             if (this.RemainingArguments.Count > 0)