diff --git a/src/coreclr/vm/datadescriptor/datadescriptor.inc b/src/coreclr/vm/datadescriptor/datadescriptor.inc
index 85d6df4ecaa043..bd2969438a8433 100644
--- a/src/coreclr/vm/datadescriptor/datadescriptor.inc
+++ b/src/coreclr/vm/datadescriptor/datadescriptor.inc
@@ -989,10 +989,21 @@ CDAC_TYPES_END()
 
 CDAC_GLOBALS_BEGIN()
 
-#if defined(TARGET_UNIX)
-CDAC_GLOBAL_STRING(OperatingSystem, unix)
+#if defined(TARGET_BROWSER)
+#ifdef Browser
+#error Handle 'Browser' define
+#endif // Browser
+CDAC_GLOBAL_STRING(OperatingSystem, Browser)
+#elif defined(TARGET_UNIX)
+#ifdef Unix
+#error Handle 'Unix' define
+#endif // Unix
+CDAC_GLOBAL_STRING(OperatingSystem, Unix)
 #elif defined(TARGET_WINDOWS)
-CDAC_GLOBAL_STRING(OperatingSystem, windows)
+#ifdef Windows
+#error Handle 'Windows' define
+#endif // Windows
+CDAC_GLOBAL_STRING(OperatingSystem, Windows)
 #else
 #error TARGET_{OS} define is not recognized by the cDAC. Update this switch and the enum values in IRuntimeInfo.cs
 #endif
diff --git a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
index 31e80c9ddc5430..99d4f1fb6dd3b9 100644
--- a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
+++ b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeInfo.cs
@@ -26,6 +26,7 @@ public enum RuntimeInfoOperatingSystem : uint
     Unknown = 0,
     Windows,
     Unix,
+    Browser,
 }
 
 public interface IRuntimeInfo : IContract
diff --git a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/AMD64/AMD64Unwinder.cs b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/AMD64/AMD64Unwinder.cs
index 404504cd79335a..53b3a5bf106e9b 100644
--- a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/AMD64/AMD64Unwinder.cs
+++ b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/AMD64/AMD64Unwinder.cs
@@ -31,7 +31,7 @@ internal class AMD64Unwinder(Target target)
     private readonly Target _target = target;
     private readonly IExecutionManager _eman = target.Contracts.ExecutionManager;
 
-    private readonly bool _unix = target.Contracts.RuntimeInfo.GetTargetOperatingSystem() == RuntimeInfoOperatingSystem.Unix;
+    private readonly bool _unixAMD64ABI = target.Contracts.RuntimeInfo.GetTargetOperatingSystem() != RuntimeInfoOperatingSystem.Windows;
 
     public bool Unwind(ref AMD64Context context)
     {
@@ -97,7 +97,7 @@ public bool Unwind(ref AMD64Context context)
         {
             frameOffset = unwindInfo.FrameOffset;
 
-            if (_unix)
+            if (_unixAMD64ABI)
             {
                 // If UnwindInfo->FrameOffset == 15 (the maximum value), then there might be a UWOP_SET_FPREG_LARGE.
                 // However, it is still legal for a UWOP_SET_FPREG to set UnwindInfo->FrameOffset == 15 (since this
@@ -133,7 +133,7 @@ public bool Unwind(ref AMD64Context context)
                 unwindOp = GetUnwindCode(unwindInfo, index);
                 if (unwindOp.UnwindOp == UnwindCode.OpCodes.UWOP_SET_FPREG)
                     break;
-                if (_unix)
+                if (_unixAMD64ABI)
                 {
                     if (unwindOp.UnwindOp == UnwindCode.OpCodes.UWOP_SET_FPREG_LARGE)
                     {
@@ -835,7 +835,7 @@ private bool UnwindPrologue(
 
                 UnwindCode unwindOp = GetUnwindCode(unwindInfo, index);
 
-                if (_unix)
+                if (_unixAMD64ABI)
                 {
                     if (unwindOp.UnwindOp > UnwindCode.OpCodes.UWOP_SET_FPREG_LARGE)
                     {
@@ -845,7 +845,8 @@ private bool UnwindPrologue(
                 }
                 else
                 {
-                    if (unwindOp.UnwindOp == UnwindCode.OpCodes.UWOP_SET_FPREG_LARGE)
+                    Debug.Assert(_target.Contracts.RuntimeInfo.GetTargetOperatingSystem() == RuntimeInfoOperatingSystem.Windows);
+                    if (unwindOp.UnwindOp > UnwindCode.OpCodes.UWOP_PUSH_MACHFRAME)
                     {
                         Debug.Fail("Expected unwind code");
                         return false;
@@ -929,7 +930,7 @@ private bool UnwindPrologue(
                         //
                         case UnwindCode.OpCodes.UWOP_SET_FPREG_LARGE:
                             {
-                                UnwinderAssert(_unix);
+                                UnwinderAssert(_unixAMD64ABI);
                                 UnwinderAssert(unwindInfo.FrameOffset == 15);
                                 uint frameOffset = GetUnwindCode(unwindInfo, index + 1).FrameOffset;
                                 frameOffset += (uint)(GetUnwindCode(unwindInfo, index + 2).FrameOffset << 16);
diff --git a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/X86/X86Unwinder.cs b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/X86/X86Unwinder.cs
index 0b90ec428403fd..547f4c104c390e 100644
--- a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/X86/X86Unwinder.cs
+++ b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/X86/X86Unwinder.cs
@@ -34,7 +34,7 @@ public class X86Unwinder(Target target)
     private readonly Target _target = target;
     private readonly uint _pointerSize = (uint)target.PointerSize;
     private readonly bool _updateAllRegs = true;
-    private readonly bool _unixX86ABI = target.Contracts.RuntimeInfo.GetTargetOperatingSystem() == RuntimeInfoOperatingSystem.Unix;
+    private readonly bool _unixX86ABI = target.Contracts.RuntimeInfo.GetTargetOperatingSystem() != RuntimeInfoOperatingSystem.Windows;
 
     private static readonly RegMask[] registerOrder =
     [
diff --git a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/SOSDacImpl.cs b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/SOSDacImpl.cs
index dd385161312b2d..4ac39286bb3dad 100644
--- a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/SOSDacImpl.cs
+++ b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/SOSDacImpl.cs
@@ -589,9 +589,10 @@ int ISOSDacInterface.GetClrWatsonBuckets(ClrDataAddress thread, void* pGenericMo
         byte[] buckets = Array.Empty<byte>();
         try
         {
-            if (_target.Contracts.RuntimeInfo.GetTargetOperatingSystem() == RuntimeInfoOperatingSystem.Unix)
+            if (_target.Contracts.RuntimeInfo.GetTargetOperatingSystem() != RuntimeInfoOperatingSystem.Windows)
                 throw Marshal.GetExceptionForHR(HResults.E_FAIL)!;
-            else if (thread == 0 || pGenericModeBlock == null)
+
+            if (thread == 0 || pGenericModeBlock == null)
                 throw new ArgumentException();
 
             buckets = threadContract.GetWatsonBuckets(thread.ToTargetPointer(_target));