diff --git a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Thread.NativeAot.Windows.cs b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Thread.NativeAot.Windows.cs
index 6382e21922029..2d782048c0147 100644
--- a/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Thread.NativeAot.Windows.cs
+++ b/src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/Thread.NativeAot.Windows.cs
@@ -253,6 +253,13 @@ private bool SetApartmentStateUnchecked(ApartmentState state, bool throwOnError)
                 {
                     if (HasStarted())
                         throw new ThreadStateException();
+
+                    // Compat: Disallow resetting the initial apartment state
+                    if (_initialApartmentState == state)
+                        return true;
+                    if (_initialApartmentState != ApartmentState.Unknown)
+                        return false;
+
                     _initialApartmentState = state;
                     return true;
                 }
diff --git a/src/coreclr/vm/comsynchronizable.cpp b/src/coreclr/vm/comsynchronizable.cpp
index 1d7fcf8b15c2c..839b957e9d300 100644
--- a/src/coreclr/vm/comsynchronizable.cpp
+++ b/src/coreclr/vm/comsynchronizable.cpp
@@ -686,25 +686,11 @@ FCIMPL2(INT32, ThreadNative::SetApartmentState, ThreadBaseObject* pThisUNSAFE, I
     if (pThisUNSAFE==NULL)
         FCThrowRes(kNullReferenceException, W("NullReference_This"));
 
-    INT32           retVal  = ApartmentUnknown;
     BOOL    ok = TRUE;
     THREADBASEREF   pThis   = (THREADBASEREF) pThisUNSAFE;
 
     HELPER_METHOD_FRAME_BEGIN_RET_1(pThis);
 
-    // Translate state input. ApartmentUnknown is not an acceptable input state.
-    // Throw an exception here rather than pass it through to the internal
-    // routine, which asserts.
-    Thread::ApartmentState state = Thread::AS_Unknown;
-    if (iState == ApartmentSTA)
-        state = Thread::AS_InSTA;
-    else if (iState == ApartmentMTA)
-        state = Thread::AS_InMTA;
-    else if (iState == ApartmentUnknown)
-        state = Thread::AS_Unknown;
-    else
-        COMPlusThrow(kArgumentOutOfRangeException, W("ArgumentOutOfRange_Enum"));
-
     Thread  *thread = pThis->GetInternal();
     if (!thread)
         COMPlusThrow(kThreadStateException, IDS_EE_THREAD_CANNOT_GET);
@@ -722,7 +708,7 @@ FCIMPL2(INT32, ThreadNative::SetApartmentState, ThreadBaseObject* pThisUNSAFE, I
         {
             EX_TRY
             {
-                state = thread->SetApartment(state);
+                iState = thread->SetApartment((Thread::ApartmentState)iState);
             }
             EX_CATCH
             {
@@ -735,24 +721,13 @@ FCIMPL2(INT32, ThreadNative::SetApartmentState, ThreadBaseObject* pThisUNSAFE, I
         pThis->LeaveObjMonitor();
     }
 
-
     // Now it's safe to throw exceptions again.
     if (!ok)
         COMPlusThrow(kThreadStateException);
 
-    // Translate state back into external form
-    if (state == Thread::AS_InSTA)
-        retVal = ApartmentSTA;
-    else if (state == Thread::AS_InMTA)
-        retVal = ApartmentMTA;
-    else if (state == Thread::AS_Unknown)
-        retVal = ApartmentUnknown;
-    else
-        _ASSERTE(!"Invalid state returned from SetApartment");
-
     HELPER_METHOD_FRAME_END();
 
-    return retVal;
+    return iState;
 }
 FCIMPLEND
 
@@ -780,10 +755,10 @@ FCIMPL1(INT32, ThreadNative::GetApartmentState, ThreadBaseObject* pThisUNSAFE)
         COMPlusThrow(kThreadStateException, W("ThreadState_Dead_State"));
     }
 
-    Thread::ApartmentState state = thread->GetApartment();
+    retVal = thread->GetApartment();
 
 #ifdef FEATURE_COMINTEROP
-    if (state == Thread::AS_Unknown)
+    if (retVal == Thread::AS_Unknown)
     {
         // If the CLR hasn't started COM yet, start it up and attempt the call again.
         // We do this in order to minimize the number of situations under which we return
@@ -791,30 +766,11 @@ FCIMPL1(INT32, ThreadNative::GetApartmentState, ThreadBaseObject* pThisUNSAFE)
         if (!g_fComStarted)
         {
             EnsureComStarted();
-            state = thread->GetApartment();
+            retVal = thread->GetApartment();
         }
     }
 #endif // FEATURE_COMINTEROP
 
-    // Translate state into external form
-    retVal = ApartmentUnknown;
-    if (state == Thread::AS_InSTA)
-    {
-        retVal = ApartmentSTA;
-    }
-    else if (state == Thread::AS_InMTA)
-    {
-        retVal = ApartmentMTA;
-    }
-    else if (state == Thread::AS_Unknown)
-    {
-        retVal = ApartmentUnknown;
-    }
-    else
-    {
-        _ASSERTE(!"Invalid state returned from GetApartment");
-    }
-
     HELPER_METHOD_FRAME_END();
 
     return retVal;
diff --git a/src/coreclr/vm/comsynchronizable.h b/src/coreclr/vm/comsynchronizable.h
index 43f998d0055af..889f99c6f3e72 100644
--- a/src/coreclr/vm/comsynchronizable.h
+++ b/src/coreclr/vm/comsynchronizable.h
@@ -52,13 +52,6 @@ friend class ThreadBaseObject;
         ThreadAbortRequested = 128,
     };
 
-    enum
-    {
-        ApartmentSTA = 0,
-        ApartmentMTA = 1,
-        ApartmentUnknown = 2
-    };
-
     static FCDECL1(INT32,   GetPriority,       ThreadBaseObject* pThisUNSAFE);
     static FCDECL2(void,    SetPriority,       ThreadBaseObject* pThisUNSAFE, INT32 iPriority);
     static FCDECL1(void,    Interrupt,         ThreadBaseObject* pThisUNSAFE);
diff --git a/src/coreclr/vm/threads.h b/src/coreclr/vm/threads.h
index ee2ca0a1de948..5aed74ef5124e 100644
--- a/src/coreclr/vm/threads.h
+++ b/src/coreclr/vm/threads.h
@@ -2654,7 +2654,9 @@ class Thread
     // undecided. The last state may indicate that the apartment has not been set at
     // all (nobody has called CoInitializeEx) or that the EE does not know the
     // current state (EE has not called CoInitializeEx).
+    // Keep in sync with System.Threading.ApartmentState
     enum ApartmentState { AS_InSTA, AS_InMTA, AS_Unknown };
+
     ApartmentState GetApartment();
     ApartmentState GetApartmentRare(Thread::ApartmentState as);
     ApartmentState GetExplicitApartment();
diff --git a/src/libraries/System.Threading.Thread/tests/ThreadTests.cs b/src/libraries/System.Threading.Thread/tests/ThreadTests.cs
index 43204224c3ef9..bb54dd600f3b8 100644
--- a/src/libraries/System.Threading.Thread/tests/ThreadTests.cs
+++ b/src/libraries/System.Threading.Thread/tests/ThreadTests.cs
@@ -253,7 +253,6 @@ public static void GetSetApartmentStateTest_ChangeAfterThreadStarted_Windows(
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsNotWindowsNanoServer))]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/34543", TestPlatforms.Windows, TargetFrameworkMonikers.Netcoreapp, TestRuntimes.Mono)]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/72232", typeof(PlatformDetection), nameof(PlatformDetection.IsNativeAot))]
         [MemberData(nameof(ApartmentStateTest_MemberData))]
         [PlatformSpecific(TestPlatforms.Windows)]  // Expected behavior differs on Unix and Windows
         public static void ApartmentStateTest_ChangeBeforeThreadStarted_Windows(
@@ -278,7 +277,6 @@ public static void ApartmentStateTest_ChangeBeforeThreadStarted_Windows(
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsWindowsNanoServer))]
         [MemberData(nameof(ApartmentStateTest_MemberData))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/72232", typeof(PlatformDetection), nameof(PlatformDetection.IsNativeAot))]
         public static void ApartmentStateTest_ChangeBeforeThreadStarted_Windows_Nano_Server(
             Func<Thread, ApartmentState> getApartmentState,
             Func<Thread, ApartmentState, int> setApartmentState,