diff --git a/NTestDataBuilder.Tests/Entities/Company.cs b/NTestDataBuilder.Tests/Entities/Company.cs
new file mode 100644
index 0000000..df0df22
--- /dev/null
+++ b/NTestDataBuilder.Tests/Entities/Company.cs
@@ -0,0 +1,16 @@
+namespace NTestDataBuilder.Tests.Entities
+{
+    public class Company
+    {
+        protected Company() { }
+
+        public Company(string name, int employeeCount)
+        {
+            Name = name;
+            EmployeeCount = employeeCount;
+        }
+
+        public virtual string Name { get; private set; }
+        public int EmployeeCount { get; private set; }
+    }
+}
diff --git a/NTestDataBuilder.Tests/NTestDataBuilder.Tests.csproj b/NTestDataBuilder.Tests/NTestDataBuilder.Tests.csproj
index 958a685..bfaefae 100644
--- a/NTestDataBuilder.Tests/NTestDataBuilder.Tests.csproj
+++ b/NTestDataBuilder.Tests/NTestDataBuilder.Tests.csproj
@@ -54,6 +54,7 @@
     <Compile Include="Builders\ProxyAlteringCustomerBuilder.cs" />
     <Compile Include="BuildTests.cs" />
     <Compile Include="CreateListTests.cs" />
+    <Compile Include="Entities\Company.cs" />
     <Compile Include="Entities\Customer.cs" />
     <Compile Include="GetOrDefaultTests.cs" />
     <Compile Include="GetSetTests.cs" />
diff --git a/NTestDataBuilder.Tests/ProxyBuilderTests.cs b/NTestDataBuilder.Tests/ProxyBuilderTests.cs
index 589bed8..2249ad5 100644
--- a/NTestDataBuilder.Tests/ProxyBuilderTests.cs
+++ b/NTestDataBuilder.Tests/ProxyBuilderTests.cs
@@ -59,5 +59,21 @@ public void GivenClassToProxyWithMultiplePropertyValues_WhenBuildingProxy_Return
             Assert.That(proxy.LastName, Is.EqualTo("LastName"));
             Assert.That(proxy.YearJoined, Is.EqualTo(1));
         }
+
+        [Test]
+        public void GivenClassWithSomeVirtualProperties_WhenBuildingProxy_ThenOnlyVirtualMembersAreProxied()
+        {
+            var proxyBuilder = new ProxyBuilder<Company>(new Dictionary<string, object>()
+            {
+                {"Name", "Vandelay Industries"},
+                {"EmployeeCount", 100}
+            });
+
+            var proxy = proxyBuilder.Build();
+
+            Assert.That(proxy.Name, Is.EqualTo("Vandelay Industries"));
+            Assert.That(proxy.EmployeeCount, Is.EqualTo(0));
+        }
     }
 }
+    
\ No newline at end of file
diff --git a/NTestDataBuilder/ProxyBuilder.cs b/NTestDataBuilder/ProxyBuilder.cs
index ab42dbc..47d6799 100644
--- a/NTestDataBuilder/ProxyBuilder.cs
+++ b/NTestDataBuilder/ProxyBuilder.cs
@@ -32,7 +32,8 @@ public T Build()
             var properties = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
             foreach (var property in properties.Where(property => _properties.ContainsKey(property.Name)))
             {
-                property.GetValue(proxy, null).Returns(_properties[property.Name]);
+                if (property.GetGetMethod().IsVirtual)
+                    property.GetValue(proxy, null).Returns(_properties[property.Name]);
             }
 
             return proxy;