diff --git a/src/Features/Core/Portable/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.Executor.cs b/src/Features/Core/Portable/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.Executor.cs
index b3900eb3a11ab5724dbf476dc52d7925cc87f4e5..2d74b51e4f13122870b77e2a61f2d147503f9954 100644
--- a/src/Features/Core/Portable/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.Executor.cs
+++ b/src/Features/Core/Portable/Diagnostics/EngineV2/DiagnosticIncrementalAnalyzer.Executor.cs
@@ -309,7 +309,9 @@ public IEnumerable<DiagnosticData> ConvertToLocalDiagnostics(Document targetDocu
                         }
 
                         // merge the result to existing one.
-                        result = result.Add(analyzer, builder.ToResult());
+                        // there can be existing one from compiler driver with empty set. overwrite it with
+                        // ide one.
+                        result = result.SetItem(analyzer, builder.ToResult());
                     }
 
                     return result;