diff --git a/MappingGenerator/MappingGenerator/MappingGenerator.Test/ImplementCloneMethod/TestCaseData/001_DeepClone.txt b/MappingGenerator/MappingGenerator/MappingGenerator.Test/ImplementCloneMethod/TestCaseData/001_DeepClone.txt
index cd7fff6..e1a9825 100644
--- a/MappingGenerator/MappingGenerator/MappingGenerator.Test/ImplementCloneMethod/TestCaseData/001_DeepClone.txt
+++ b/MappingGenerator/MappingGenerator/MappingGenerator.Test/ImplementCloneMethod/TestCaseData/001_DeepClone.txt
@@ -26,6 +26,7 @@ namespace MappingGenerator.Test.MappingGenerator.TestCaseData
         public AddressDTO MainAddress { get; set; }
         public ReadOnlyCollection<AddressDTO> Addresses { get; set; }
         public int UnitId { get; set; }
+        public int? Rate { get; set; }
     }
 
     public class UserSourceDTO
diff --git a/MappingGenerator/MappingGenerator/MappingGenerator.Test/ImplementCloneMethod/TestCaseData/001_DeepClone_FIXED.txt b/MappingGenerator/MappingGenerator/MappingGenerator.Test/ImplementCloneMethod/TestCaseData/001_DeepClone_FIXED.txt
index f639a42..9a4d039 100644
--- a/MappingGenerator/MappingGenerator/MappingGenerator.Test/ImplementCloneMethod/TestCaseData/001_DeepClone_FIXED.txt
+++ b/MappingGenerator/MappingGenerator/MappingGenerator.Test/ImplementCloneMethod/TestCaseData/001_DeepClone_FIXED.txt
@@ -26,6 +26,7 @@ namespace MappingGenerator.Test.MappingGenerator.TestCaseData
         public AddressDTO MainAddress { get; set; }
         public ReadOnlyCollection<AddressDTO> Addresses { get; set; }
         public int UnitId { get; set; }
+        public int? Rate { get; set; }
 
         public UserDTO Clone()
         {
@@ -59,6 +60,7 @@ namespace MappingGenerator.Test.MappingGenerator.TestCaseData
                     BuildingNo = thisAddress.BuildingNo
                 }).ToList().AsReadOnly(),
                 UnitId = UnitId,
+                Rate = Rate,
                 Id = Id
             };
         }
diff --git a/MappingGenerator/MappingGenerator/MappingGenerator/CloneMappingEngine.cs b/MappingGenerator/MappingGenerator/MappingGenerator/CloneMappingEngine.cs
index 6dedcc3..d6cb286 100644
--- a/MappingGenerator/MappingGenerator/MappingGenerator/CloneMappingEngine.cs
+++ b/MappingGenerator/MappingGenerator/MappingGenerator/CloneMappingEngine.cs
@@ -16,6 +16,11 @@ public CloneMappingEngine(SemanticModel semanticModel, SyntaxGenerator syntaxGen
 
         protected override bool ShouldCreateConversionBetweenTypes(ITypeSymbol targetType, ITypeSymbol sourceType)
         {
+            if (targetType.Equals(sourceType) && SymbolHelper.IsNullable(targetType, out _))
+            {
+                return false;
+            }
+
             return  ObjectHelper.IsSimpleType(targetType) == false && ObjectHelper.IsSimpleType(sourceType) == false;
         }