diff --git a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Thread.NativeAot.cs b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Thread.NativeAot.cs
index ba2550eb364aba..2564eec546c229 100644
--- a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Thread.NativeAot.cs
+++ b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Thread.NativeAot.cs
@@ -369,7 +369,7 @@ private void StartCore()
                 if (GetThreadStateBit(ThreadState.Unstarted))
                 {
                     Exception? startException = _startException;
-                    startException = null;
+                    _startException = null;
 
                     throw new ThreadStartException(startException ?? new OutOfMemoryException());
                 }
diff --git a/src/libraries/System.Threading.Thread/tests/ThreadTests.cs b/src/libraries/System.Threading.Thread/tests/ThreadTests.cs
index cf6c5e0c31f6a4..09dc1d0b5ce342 100644
--- a/src/libraries/System.Threading.Thread/tests/ThreadTests.cs
+++ b/src/libraries/System.Threading.Thread/tests/ThreadTests.cs
@@ -291,7 +291,8 @@ public static void ApartmentStateTest_ChangeBeforeThreadStarted_Windows_Nano_Ser
             Assert.Equal(setType == 0 ? 0 : 2, setApartmentState(t, ApartmentState.MTA)); // cannot be changed more than once
             Assert.Equal(ApartmentState.STA, getApartmentState(t));
 
-            Assert.Throws<ThreadStartException>(() => t.Start()); // Windows Nano Server does not support starting threads in the STA.
+            Exception ex = Assert.Throws<ThreadStartException>(() => t.Start()); // Windows Nano Server does not support starting threads in the STA.
+            Assert.IsType<PlatformNotSupportedException>(ex.InnerException);
         }