diff --git a/src/Analyzers/Core/Analyzers/IDEDiagnosticIds.cs b/src/Analyzers/Core/Analyzers/IDEDiagnosticIds.cs
index 6875e9a3fef22..deb526ecc79e6 100644
--- a/src/Analyzers/Core/Analyzers/IDEDiagnosticIds.cs
+++ b/src/Analyzers/Core/Analyzers/IDEDiagnosticIds.cs
@@ -16,7 +16,9 @@ internal static class IDEDiagnosticIds
     public const string RemoveUnnecessaryImportsDiagnosticId = "IDE0005";
     public const string RemoveUnnecessaryImportsGeneratedCodeDiagnosticId = RemoveUnnecessaryImportsDiagnosticId + "_gen";
 
-    public const string IntellisenseBuildFailedDiagnosticId = "IDE0006";
+    // No longer used. Avoid re-using the same ID again.
+    // public const string IntellisenseBuildFailedDiagnosticId = "IDE0006";
+
     public const string UseImplicitTypeDiagnosticId = "IDE0007";
     public const string UseExplicitTypeDiagnosticId = "IDE0008";
     public const string AddThisOrMeQualificationDiagnosticId = "IDE0009";