diff --git a/conventions/editorconfig-csharp/files/.editorconfig b/conventions/editorconfig-csharp/files/.editorconfig
index 12b06e3..5cc0e12 100644
--- a/conventions/editorconfig-csharp/files/.editorconfig
+++ b/conventions/editorconfig-csharp/files/.editorconfig
@@ -197,7 +197,7 @@ dotnet_diagnostic.IDE0305.severity = suggestion
 dotnet_diagnostic.IDE0306.severity = suggestion
 dotnet_diagnostic.IDE0370.severity = suggestion
 dotnet_diagnostic.IDE0390.severity = suggestion
-dotnet_diagnostic.IDE0391.severity = suggestion
+dotnet_diagnostic.IDE0391.severity = none
 dotnet_diagnostic.IDE1005.severity = suggestion
 dotnet_diagnostic.NUnit2045.severity = suggestion
 dotnet_diagnostic.SA0001.severity = none
diff --git a/sections/csharp/editorconfig.md b/sections/csharp/editorconfig.md
index 8441b7b..140c07d 100644
--- a/sections/csharp/editorconfig.md
+++ b/sections/csharp/editorconfig.md
@@ -323,7 +323,7 @@ As of this writing, detection of unnecessary nullable warning suppressions using
 
 ```editorconfig
 dotnet_diagnostic.IDE0390.severity = suggestion
-dotnet_diagnostic.IDE0391.severity = suggestion
+dotnet_diagnostic.IDE0391.severity = none
 ```
 
 We prefer to use the `async` keyword for cleaner code, even when it is less efficient than returning `Task.FromResult` or `Task.CompletedTask`.