diff --git a/flang/include/flang/Evaluate/tools.h b/flang/include/flang/Evaluate/tools.h
index 352f6b36458c..f94981011b6e 100644
--- a/flang/include/flang/Evaluate/tools.h
+++ b/flang/include/flang/Evaluate/tools.h
@@ -1417,8 +1417,8 @@ inline bool IsAssumedSizeArray(const Symbol &symbol) {
 // In a SELECT RANK construct, ResolveAssociations() stops at a
 // RANK(n) or RANK(*) case symbol, but traverses the selector for
 // RANK DEFAULT.
-const Symbol &ResolveAssociations(const Symbol &);
-const Symbol &GetAssociationRoot(const Symbol &);
+const Symbol &ResolveAssociations(const Symbol &, bool stopAtTypeGuard = false);
+const Symbol &GetAssociationRoot(const Symbol &, bool stopAtTypeGuard = false);
 
 const Symbol *FindCommonBlockContaining(const Symbol &);
 int CountLenParameters(const DerivedTypeSpec &);
diff --git a/flang/include/flang/Semantics/symbol.h b/flang/include/flang/Semantics/symbol.h
index 4ae2775c0f84..715811885c21 100644
--- a/flang/include/flang/Semantics/symbol.h
+++ b/flang/include/flang/Semantics/symbol.h
@@ -329,9 +329,11 @@ public:
   }
   bool IsAssumedSize() const { return rank_.value_or(0) == isAssumedSize; }
   bool IsAssumedRank() const { return rank_.value_or(0) == isAssumedRank; }
+  bool isTypeGuard() const { return isTypeGuard_; }
   void set_rank(int rank);
   void set_IsAssumedSize();
   void set_IsAssumedRank();
+  void set_isTypeGuard(bool yes = true);
 
 private:
   MaybeExpr expr_;
@@ -340,6 +342,7 @@ private:
   static constexpr int isAssumedSize{-1}; // RANK(*)
   static constexpr int isAssumedRank{-2}; // RANK DEFAULT
   std::optional<int> rank_;
+  bool isTypeGuard_{false}; // TYPE IS or CLASS IS, but not CLASS(DEFAULT)
 };
 llvm::raw_ostream &operator<<(llvm::raw_ostream &, const AssocEntityDetails &);
 
diff --git a/flang/lib/Evaluate/tools.cpp b/flang/lib/Evaluate/tools.cpp
index 7181265b862f..36b7d0a69d2b 100644
--- a/flang/lib/Evaluate/tools.cpp
+++ b/flang/lib/Evaluate/tools.cpp
@@ -1540,10 +1540,12 @@ bool CheckForCoindexedObject(parser::ContextualMessages &messages,
 
 namespace Fortran::semantics {
 
-const Symbol &ResolveAssociations(const Symbol &original) {
+const Symbol &ResolveAssociations(
+    const Symbol &original, bool stopAtTypeGuard) {
   const Symbol &symbol{original.GetUltimate()};
   if (const auto *details{symbol.detailsIf<AssocEntityDetails>()}) {
-    if (!details->rank()) { // Not RANK(n) or RANK(*)
+    if (!details->rank() /* not RANK(n) or RANK(*) */ &&
+        !(stopAtTypeGuard && details->isTypeGuard())) {
       if (const Symbol * nested{UnwrapWholeSymbolDataRef(details->expr())}) {
         return ResolveAssociations(*nested);
       }
@@ -1567,8 +1569,8 @@ static const Symbol *GetAssociatedVariable(const AssocEntityDetails &details) {
   return nullptr;
 }
 
-const Symbol &GetAssociationRoot(const Symbol &original) {
-  const Symbol &symbol{ResolveAssociations(original)};
+const Symbol &GetAssociationRoot(const Symbol &original, bool stopAtTypeGuard) {
+  const Symbol &symbol{ResolveAssociations(original, stopAtTypeGuard)};
   if (const auto *details{symbol.detailsIf<AssocEntityDetails>()}) {
     if (const Symbol * root{GetAssociatedVariable(*details)}) {
       return *root;
diff --git a/flang/lib/Semantics/check-call.cpp b/flang/lib/Semantics/check-call.cpp
index 8485a7a1f5bc..4042d7504396 100644
--- a/flang/lib/Semantics/check-call.cpp
+++ b/flang/lib/Semantics/check-call.cpp
@@ -535,9 +535,6 @@ static void CheckExplicitDataArg(const characteristics::DummyDataObject &dummy,
   if (actualLastSymbol) {
     actualLastSymbol = &ResolveAssociations(*actualLastSymbol);
   }
-  const ObjectEntityDetails *actualLastObject{actualLastSymbol
-          ? actualLastSymbol->detailsIf<ObjectEntityDetails>()
-          : nullptr};
   int actualRank{actualType.Rank()};
   if (dummy.type.attrs().test(
           characteristics::TypeAndShape::Attr::AssumedShape)) {
@@ -689,6 +686,9 @@ static void CheckExplicitDataArg(const characteristics::DummyDataObject &dummy,
       }
     }
   }
+  const ObjectEntityDetails *actualLastObject{actualLastSymbol
+          ? actualLastSymbol->detailsIf<ObjectEntityDetails>()
+          : nullptr};
   if (actualLastObject && actualLastObject->IsCoarray() &&
       dummy.attrs.test(characteristics::DummyDataObject::Attr::Allocatable) &&
       dummy.intent == common::Intent::Out &&
diff --git a/flang/lib/Semantics/check-do-forall.cpp b/flang/lib/Semantics/check-do-forall.cpp
index 84e6b6455cc6..cc1d4bf58745 100644
--- a/flang/lib/Semantics/check-do-forall.cpp
+++ b/flang/lib/Semantics/check-do-forall.cpp
@@ -154,7 +154,8 @@ public:
   // of its components?
   static bool MightDeallocatePolymorphic(const Symbol &original,
       const std::function<bool(const Symbol &)> &WillDeallocate) {
-    const Symbol &symbol{ResolveAssociations(original)};
+    const Symbol &symbol{
+        ResolveAssociations(original, /*stopAtTypeGuard=*/true)};
     // Check the entity itself, no coarray exception here
     if (IsPolymorphicAllocatable(symbol)) {
       return true;
@@ -182,11 +183,10 @@ public:
         impure.name(), reason);
   }
 
-  void SayDeallocateOfPolymorph(
+  void SayDeallocateOfPolymorphic(
       parser::CharBlock location, const Symbol &entity, const char *reason) {
     context_.SayWithDecl(entity, location,
-        "Deallocation of a polymorphic entity caused by %s"
-        " not allowed in DO CONCURRENT"_err_en_US,
+        "Deallocation of a polymorphic entity caused by %s not allowed in DO CONCURRENT"_err_en_US,
         reason);
   }
 
@@ -206,7 +206,7 @@ public:
         const Symbol &entity{*pair.second};
         if (IsAllocatable(entity) && !IsSaved(entity) &&
             MightDeallocatePolymorphic(entity, DeallocateAll)) {
-          SayDeallocateOfPolymorph(endBlockStmt.source, entity, reason);
+          SayDeallocateOfPolymorphic(endBlockStmt.source, entity, reason);
         }
         if (const Symbol * impure{HasImpureFinal(entity)}) {
           SayDeallocateWithImpureFinal(entity, reason, *impure);
@@ -222,7 +222,7 @@ public:
     if (const Symbol * entity{GetLastName(variable).symbol}) {
       const char *reason{"assignment"};
       if (MightDeallocatePolymorphic(*entity, DeallocateNonCoarray)) {
-        SayDeallocateOfPolymorph(variable.GetSource(), *entity, reason);
+        SayDeallocateOfPolymorphic(variable.GetSource(), *entity, reason);
       }
       if (const auto *assignment{GetAssignment(stmt)}) {
         const auto &lhs{assignment->lhs};
@@ -257,7 +257,7 @@ public:
         const DeclTypeSpec *entityType{entity.GetType()};
         if ((entityType && entityType->IsPolymorphic()) || // POINTER case
             MightDeallocatePolymorphic(entity, DeallocateAll)) {
-          SayDeallocateOfPolymorph(
+          SayDeallocateOfPolymorphic(
               currentStatementSourcePosition_, entity, reason);
         }
         if (const Symbol * impure{HasImpureFinal(entity)}) {
diff --git a/flang/lib/Semantics/expression.cpp b/flang/lib/Semantics/expression.cpp
index 6949e5693d08..82e346bb4b6d 100644
--- a/flang/lib/Semantics/expression.cpp
+++ b/flang/lib/Semantics/expression.cpp
@@ -3289,7 +3289,7 @@ const Assignment *ExpressionAnalyzer::Analyze(const parser::AssignmentStmt &x) {
             dyType && dyType->IsPolymorphic()) { // 10.2.1.2p1(1)
           const Symbol *lastWhole0{UnwrapWholeSymbolOrComponentDataRef(lhs)};
           const Symbol *lastWhole{
-              lastWhole0 ? &lastWhole0->GetUltimate() : nullptr};
+              lastWhole0 ? &ResolveAssociations(*lastWhole0) : nullptr};
           if (!lastWhole || !IsAllocatable(*lastWhole)) {
             Say("Left-hand side of assignment may not be polymorphic unless assignment is to an entire allocatable"_err_en_US);
           } else if (evaluate::IsCoarray(*lastWhole)) {
diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index 514c0b88d350..1514c01a4952 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -7748,6 +7748,7 @@ void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
       SetTypeFromAssociation(*symbol);
     } else if (const auto *type{GetDeclTypeSpec()}) {
       symbol->SetType(*type);
+      symbol->get<AssocEntityDetails>().set_isTypeGuard();
     }
     SetAttrsFromAssociation(*symbol);
   }
diff --git a/flang/lib/Semantics/symbol.cpp b/flang/lib/Semantics/symbol.cpp
index 61982295f323..32eb6c2c5a18 100644
--- a/flang/lib/Semantics/symbol.cpp
+++ b/flang/lib/Semantics/symbol.cpp
@@ -155,6 +155,7 @@ void EntityDetails::set_type(const DeclTypeSpec &type) {
 void AssocEntityDetails::set_rank(int rank) { rank_ = rank; }
 void AssocEntityDetails::set_IsAssumedSize() { rank_ = isAssumedSize; }
 void AssocEntityDetails::set_IsAssumedRank() { rank_ = isAssumedRank; }
+void AssocEntityDetails::set_isTypeGuard(bool yes) { isTypeGuard_ = yes; }
 void EntityDetails::ReplaceType(const DeclTypeSpec &type) { type_ = &type; }
 
 ObjectEntityDetails::ObjectEntityDetails(EntityDetails &&d)
diff --git a/flang/lib/Semantics/tools.cpp b/flang/lib/Semantics/tools.cpp
index 5bb8bae83a78..5e58a0c75c77 100644
--- a/flang/lib/Semantics/tools.cpp
+++ b/flang/lib/Semantics/tools.cpp
@@ -633,9 +633,9 @@ const EquivalenceSet *FindEquivalenceSet(const Symbol &symbol) {
 }
 
 bool IsOrContainsEventOrLockComponent(const Symbol &original) {
-  const Symbol &symbol{ResolveAssociations(original)};
-  if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
-    if (const DeclTypeSpec * type{details->type()}) {
+  const Symbol &symbol{ResolveAssociations(original, /*stopAtTypeGuard=*/true)};
+  if (evaluate::IsVariable(symbol)) {
+    if (const DeclTypeSpec * type{symbol.GetType()}) {
       if (const DerivedTypeSpec * derived{type->AsDerived()}) {
         return IsEventTypeOrLockType(derived) ||
             FindEventOrLockPotentialComponent(*derived);
@@ -849,7 +849,7 @@ static const Symbol *HasImpureFinal(
 }
 
 const Symbol *HasImpureFinal(const Symbol &original, std::optional<int> rank) {
-  const Symbol &symbol{ResolveAssociations(original)};
+  const Symbol &symbol{ResolveAssociations(original, /*stopAtTypeGuard=*/true)};
   if (symbol.has<ObjectEntityDetails>()) {
     if (const DeclTypeSpec * symType{symbol.GetType()}) {
       if (const DerivedTypeSpec * derived{symType->AsDerived()}) {
diff --git a/flang/test/Semantics/doconcurrent08.f90 b/flang/test/Semantics/doconcurrent08.f90
index e09d1ab32acb..48d653fc6589 100644
--- a/flang/test/Semantics/doconcurrent08.f90
+++ b/flang/test/Semantics/doconcurrent08.f90
@@ -125,6 +125,8 @@ subroutine s2()
   class(Base), allocatable, codimension[:] :: allocPolyComponentVar
   class(Base), allocatable, codimension[:] :: allocPolyComponentVar1
 
+  class(*), allocatable :: unlimitedPoly
+
   allocate(ChildType :: localVar)
   allocate(ChildType :: localVar1)
   allocate(Base :: localVar2)
@@ -162,6 +164,16 @@ subroutine s2()
 !ERROR: Deallocation of a polymorphic entity caused by assignment not allowed in DO CONCURRENT
     allocPolyCoarray = allocPolyCoarray1
 
+!ERROR: Deallocation of a polymorphic entity caused by assignment not allowed in DO CONCURRENT
+    unlimitedPoly = 1
+    select type (unlimitedPoly)
+    type is (integer)
+      unlimitedPoly = 1 ! ok
+    class default
+!ERROR: Deallocation of a polymorphic entity caused by assignment not allowed in DO CONCURRENT
+      unlimitedPoly = 1
+    end select
+
   end do
 end subroutine s2