diff --git a/src/Pose/IL/Stubs.cs b/src/Pose/IL/Stubs.cs
index 48b2483..118620f 100644
--- a/src/Pose/IL/Stubs.cs
+++ b/src/Pose/IL/Stubs.cs
@@ -173,7 +173,7 @@ public static DynamicMethod GenerateStubForDirectCall(MethodBase method)
 
             ilGenerator.MarkLabel(returnLabel);
             ilGenerator.Emit(OpCodes.Ret);
-
+            
             return stub;
         }
 
@@ -451,7 +451,7 @@ public static DynamicMethod GenerateStubForObjectInitialization(ConstructorInfo
             ilGenerator.MarkLabel(rewriteLabel);
             
             // ++
-            if (thisType.IsValueType)
+            if (constructor.DeclaringType.IsValueType)
             {
                 ilGenerator.Emit(OpCodes.Ldloca_S, (byte)1);
                 // ilGenerator.Emit(OpCodes.Dup);
diff --git a/test/Pose.Tests/RegressionTests.cs b/test/Pose.Tests/RegressionTests.cs
new file mode 100644
index 0000000..7718ccd
--- /dev/null
+++ b/test/Pose.Tests/RegressionTests.cs
@@ -0,0 +1,32 @@
+using System;
+using FluentAssertions;
+using Xunit;
+using DateTime = System.DateTime;
+
+namespace Pose.Tests
+{
+    public class RegressionTests
+    {
+        private enum TestEnum { A }
+        
+        [Fact(DisplayName = "Enum.IsDefined cannot be called from within PoseContext.Isolate #26")]
+        public void Can_call_EnumIsDefined_from_Isolate()
+        {
+            // Arrange
+            var shim = Shim
+                .Replace(() => new DateTime(2024, 2, 2))
+                .With((int year, int month, int day) => new DateTime(2004, 1, 1));
+            var isDefined = false;
+            
+            // Act
+            PoseContext.Isolate(
+                () =>
+                {
+                    isDefined = Enum.IsDefined(typeof(TestEnum), nameof(TestEnum.A));
+                }, shim);
+            
+            // Assert
+            isDefined.Should().BeTrue(because: "Enum.IsDefined can be called from Isolate");
+        }
+    }
+}
\ No newline at end of file