diff --git a/src/EFCore.Relational/Query/QuerySqlGenerator.cs b/src/EFCore.Relational/Query/QuerySqlGenerator.cs
index 9f159d7752b..91949ff4cf4 100644
--- a/src/EFCore.Relational/Query/QuerySqlGenerator.cs
+++ b/src/EFCore.Relational/Query/QuerySqlGenerator.cs
@@ -292,7 +292,7 @@ protected override Expression VisitSqlFunction(SqlFunctionExpression sqlFunction
             if (!sqlFunctionExpression.IsNiladic)
             {
                 _relationalCommandBuilder.Append("(");
-                GenerateList(sqlFunctionExpression.Arguments!, e => Visit(e));
+                GenerateList(sqlFunctionExpression.Arguments, e => Visit(e));
                 _relationalCommandBuilder.Append(")");
             }
 
diff --git a/src/EFCore.Relational/Query/SqlExpressions/SqlFunctionExpression.cs b/src/EFCore.Relational/Query/SqlExpressions/SqlFunctionExpression.cs
index 6f5855a5c4f..8f360cf2ec4 100644
--- a/src/EFCore.Relational/Query/SqlExpressions/SqlFunctionExpression.cs
+++ b/src/EFCore.Relational/Query/SqlExpressions/SqlFunctionExpression.cs
@@ -9,6 +9,7 @@
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore.Storage;
 using Microsoft.EntityFrameworkCore.Utilities;
+using CA = System.Diagnostics.CodeAnalysis;
 
 #nullable enable
 namespace Microsoft.EntityFrameworkCore.Query.SqlExpressions
@@ -22,7 +23,6 @@ namespace Microsoft.EntityFrameworkCore.Query.SqlExpressions
     ///         not used in application code.
     ///     </para>
     /// </summary>
-    // TODO - NULLABLE for C# 9 (MemberNotNullIf on IsNiladic)
     public class SqlFunctionExpression : SqlExpression
     {
         /// <summary>
@@ -231,6 +231,7 @@ private SqlFunctionExpression(
         /// <summary>
         ///     A bool value indicating if the function is niladic.
         /// </summary>
+        [CA.MemberNotNullWhen(false, nameof(Arguments), nameof(ArgumentsPropagateNullability))]
         public virtual bool IsNiladic { get; }
 
         /// <summary>
@@ -276,7 +277,7 @@ protected override Expression VisitChildren(ExpressionVisitor visitor)
             SqlExpression[]? arguments = default;
             if (!IsNiladic)
             {
-                arguments = new SqlExpression[Arguments!.Count];
+                arguments = new SqlExpression[Arguments.Count];
                 for (var i = 0; i < arguments.Length; i++)
                 {
                     arguments[i] = (SqlExpression)visitor.Visit(Arguments[i]);
@@ -367,7 +368,7 @@ protected override void Print(ExpressionPrinter expressionPrinter)
             if (!IsNiladic)
             {
                 expressionPrinter.Append("(");
-                expressionPrinter.VisitCollection(Arguments!);
+                expressionPrinter.VisitCollection(Arguments);
                 expressionPrinter.Append(")");
             }
         }
@@ -381,6 +382,7 @@ public override bool Equals(object? obj)
 
         private bool Equals(SqlFunctionExpression sqlFunctionExpression)
             => base.Equals(sqlFunctionExpression)
+                && IsNiladic == sqlFunctionExpression.IsNiladic
                 && Name == sqlFunctionExpression.Name
                 && Schema == sqlFunctionExpression.Schema
                 && ((Instance == null && sqlFunctionExpression.Instance == null)
diff --git a/src/EFCore.Relational/Query/SqlNullabilityProcessor.cs b/src/EFCore.Relational/Query/SqlNullabilityProcessor.cs
index aca2234f270..ae66ec72efb 100644
--- a/src/EFCore.Relational/Query/SqlNullabilityProcessor.cs
+++ b/src/EFCore.Relational/Query/SqlNullabilityProcessor.cs
@@ -1002,7 +1002,7 @@ protected virtual SqlExpression VisitSqlFunction(
                 return sqlFunctionExpression.Update(instance, sqlFunctionExpression.Arguments);
             }
 
-            var arguments = new SqlExpression[sqlFunctionExpression.Arguments!.Count];
+            var arguments = new SqlExpression[sqlFunctionExpression.Arguments.Count];
             for (var i = 0; i < arguments.Length; i++)
             {
                 arguments[i] = Visit(sqlFunctionExpression.Arguments[i], out _);
@@ -1687,8 +1687,7 @@ private SqlExpression ProcessNullNotNull(SqlUnaryExpression sqlUnaryExpression,
                         nullabilityPropagationElements.Add(sqlFunctionExpression.Instance);
                     }
 
-                    if (sqlFunctionExpression.Arguments != null
-                        && sqlFunctionExpression.ArgumentsPropagateNullability != null)
+                    if (!sqlFunctionExpression.IsNiladic)
                     {
                         for (var i = 0; i < sqlFunctionExpression.Arguments.Count; i++)
                         {
diff --git a/src/EFCore.SqlServer/Query/Internal/SearchConditionConvertingExpressionVisitor.cs b/src/EFCore.SqlServer/Query/Internal/SearchConditionConvertingExpressionVisitor.cs
index cb64d328a74..36fe2dc7adc 100644
--- a/src/EFCore.SqlServer/Query/Internal/SearchConditionConvertingExpressionVisitor.cs
+++ b/src/EFCore.SqlServer/Query/Internal/SearchConditionConvertingExpressionVisitor.cs
@@ -453,7 +453,7 @@ protected override Expression VisitSqlFunction(SqlFunctionExpression sqlFunction
             SqlExpression[]? arguments = default;
             if (!sqlFunctionExpression.IsNiladic)
             {
-                arguments = new SqlExpression[sqlFunctionExpression.Arguments!.Count];
+                arguments = new SqlExpression[sqlFunctionExpression.Arguments.Count];
                 for (var i = 0; i < arguments.Length; i++)
                 {
                     arguments[i] = (SqlExpression)Visit(sqlFunctionExpression.Arguments[i]);