diff --git a/src/IKVM.MSBuild.Tasks/IkvmToolTaskDiagnosticWriter.cs b/src/IKVM.MSBuild.Tasks/IkvmToolTaskDiagnosticWriter.cs
index 259b27dd0..fd83ff806 100644
--- a/src/IKVM.MSBuild.Tasks/IkvmToolTaskDiagnosticWriter.cs
+++ b/src/IKVM.MSBuild.Tasks/IkvmToolTaskDiagnosticWriter.cs
@@ -54,10 +54,10 @@ public async ValueTask ReceiveAsync(IkvmToolDiagnosticEvent @event, Cancellation
                         logger.LogWarning(null, $"{@event.Id:D4}", null, null, @event.Location.StartLine, @event.Location.StartColumn, @event.Location.EndLine, @event.Location.EndColumn, @event.Message, @event.Args);
                         break;
                     case IkvmToolDiagnosticEventLevel.Error:
-                        logger.LogError(null, $"{@event.Id:D4}", null, null, @event.Location.StartLine, @event.Location.StartColumn, @event.Location.EndLine, @event.Location.EndColumn, MessageImportance.Normal, @event.Message, @event.Args);
+                        logger.LogError(null, $"{@event.Id:D4}", null, null, @event.Location.StartLine, @event.Location.StartColumn, @event.Location.EndLine, @event.Location.EndColumn, @event.Message, @event.Args);
                         break;
                     case IkvmToolDiagnosticEventLevel.Fatal:
-                        logger.LogError(null, $"{@event.Id:D4}", null, null, @event.Location.StartLine, @event.Location.StartColumn, @event.Location.EndLine, @event.Location.EndColumn, MessageImportance.High, @event.Message, @event.Args);
+                        logger.LogError(null, $"{@event.Id:D4}", null, null, @event.Location.StartLine, @event.Location.StartColumn, @event.Location.EndLine, @event.Location.EndColumn, @event.Message, @event.Args);
                         break;
                 }
 
diff --git a/src/IKVM.Tools.Importer/ImportContext.cs b/src/IKVM.Tools.Importer/ImportContext.cs
index d0a2a78d5..7341ba770 100644
--- a/src/IKVM.Tools.Importer/ImportContext.cs
+++ b/src/IKVM.Tools.Importer/ImportContext.cs
@@ -569,7 +569,7 @@ void ContinueParseCommandLine(RuntimeContext context, StaticCompiler compiler, I
 
             if (options.NoWarn != null)
                 foreach (var diagnostic in options.NoWarn)
-                    compilerOptions.suppressWarnings.Add($"IKVM{diagnostic.Id:D4}");
+                    compilerOptions.suppressWarnings.Add(diagnostic.Id.ToString());
 
             // TODO handle specific diagnostic IDs
             if (options.WarnAsError != null)
@@ -578,7 +578,7 @@ void ContinueParseCommandLine(RuntimeContext context, StaticCompiler compiler, I
                     compilerOptions.warnaserror = true;
                 else
                     foreach (var i in options.WarnAsError)
-                        compilerOptions.errorWarnings.Add($"IKVM{i.Id:D4}");
+                        compilerOptions.errorWarnings.Add(i.Id.ToString());
             }
 
             if (options.Runtime != null)