diff --git a/ChangeLog.md b/ChangeLog.md
index 76d113c974..f0629df64f 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Improve inversion of logical expressions to handling additional cases ([#1086](https://github.com/josefpihrt/roslynator/pull/1086)).
 - Fix [RCS1084](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1084.md) ([#1085](https://github.com/josefpihrt/roslynator/pull/1085)).
+- Fix [RCS1169](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1169.md) ([#1092](https://github.com/JosefPihrt/Roslynator/pull/1092)).
 
 ## [4.3.0] - 2023-04-24
 
diff --git a/src/Analyzers/CSharp/Analysis/MakeMemberReadOnly/MakeMemberReadOnlyWalker.cs b/src/Analyzers/CSharp/Analysis/MakeMemberReadOnly/MakeMemberReadOnlyWalker.cs
index ffdc44955e..baab24a662 100644
--- a/src/Analyzers/CSharp/Analysis/MakeMemberReadOnly/MakeMemberReadOnlyWalker.cs
+++ b/src/Analyzers/CSharp/Analysis/MakeMemberReadOnly/MakeMemberReadOnlyWalker.cs
@@ -67,6 +67,13 @@ public override void VisitAssignedExpression(ExpressionSyntax expression)
     {
         SyntaxKind kind = expression.Kind();
 
+        if (kind == SyntaxKind.SuppressNullableWarningExpression)
+        {
+            var postfixUnaryExpression = (PostfixUnaryExpressionSyntax)expression;
+            expression = postfixUnaryExpression.Operand;
+            kind = expression.Kind();
+        }
+
         if (kind == SyntaxKind.IdentifierName)
         {
             AnalyzeAssigned((IdentifierNameSyntax)expression);
@@ -130,10 +137,8 @@ public override void VisitRefExpression(RefExpressionSyntax node)
         {
             VisitAssignedExpression(expression);
         }
-        else
-        {
-            base.VisitRefExpression(node);
-        }
+
+        base.VisitRefExpression(node);
     }
 
     public override void VisitLocalFunctionStatement(LocalFunctionStatementSyntax node)
diff --git a/src/Tests/Analyzers.Tests/RCS1169MakeFieldReadOnlyTests.cs b/src/Tests/Analyzers.Tests/RCS1169MakeFieldReadOnlyTests.cs
index c8f0fe2bb9..2c7fa37c51 100644
--- a/src/Tests/Analyzers.Tests/RCS1169MakeFieldReadOnlyTests.cs
+++ b/src/Tests/Analyzers.Tests/RCS1169MakeFieldReadOnlyTests.cs
@@ -348,6 +348,33 @@ ref int M()
         return ref _f;
     }
 }
+");
+    }
+    
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.MakeFieldReadOnly)]
+    public async Task TestNoDiagnostic_SuppressNullableWarning()
+    {
+        await VerifyNoDiagnosticAsync(@"
+class C
+{
+    int _a;
+
+    void M(ref int x) {}
+    void M2() {M(ref _a!);} 
+}
+");
+    }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.MakeFieldReadOnly)]
+    public async Task TestNoDiagnostic_RefInRef()
+    {
+        await VerifyNoDiagnosticAsync(@"
+using System.Runtime.CompilerServices;
+class C
+{
+    int _a;
+    ref int M2() {return ref Unsafe.Add(ref _a, 3);} 
+}
 ");
     }
 }