diff --git a/flang/lib/Optimizer/Builder/FIRBuilder.cpp b/flang/lib/Optimizer/Builder/FIRBuilder.cpp
--- a/flang/lib/Optimizer/Builder/FIRBuilder.cpp
+++ b/flang/lib/Optimizer/Builder/FIRBuilder.cpp
@@ -516,11 +516,17 @@
         << itemAddr.getType();
     llvm_unreachable("not a memory reference type");
   }
-  mlir::Type boxTy = fir::BoxType::get(elementType);
+  mlir::Type boxTy;
   mlir::Value tdesc;
-  if (isPolymorphic) {
-    elementType = fir::updateTypeForUnlimitedPolymorphic(elementType);
-    boxTy = fir::ClassType::get(elementType);
+  // Avoid to wrap a box/class with box/class.
+  if (elementType.isa<fir::BaseBoxType>()) {
+    boxTy = elementType;
+  } else {
+    boxTy = fir::BoxType::get(elementType);
+    if (isPolymorphic) {
+      elementType = fir::updateTypeForUnlimitedPolymorphic(elementType);
+      boxTy = fir::ClassType::get(elementType);
+    }
   }
 
   return exv.match(
diff --git a/flang/test/Lower/polymorphic.f90 b/flang/test/Lower/polymorphic.f90
--- a/flang/test/Lower/polymorphic.f90
+++ b/flang/test/Lower/polymorphic.f90
@@ -1086,6 +1086,32 @@
 ! CHECK: %[[CONV:.*]] = fir.convert %[[RES]] : (!fir.box<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>>) -> !fir.class<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>>
 ! CHECK: fir.call @_QMpolymorphic_testPtakes_p1_opt(%[[CONV]]) {{.*}} : (!fir.class<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>>) -> ()
 
+  subroutine class_with_entry(a)
+    class(p1) :: a,b
+    select type (a)
+    type is(p2)
+      print*, a%c
+    class default
+      print*, a%a
+    end select
+    return
+  entry d(b)
+    select type(b)
+    type is(p2)
+      print*,b%c
+    class default
+      print*,b%a
+    end select
+  end subroutine
+
+! CHECK-LABEL: func.func @_QMpolymorphic_testPclass_with_entry(
+! CHECK-SAME: %[[A:.*]]: !fir.class<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>> {fir.bindc_name = "a"}) {
+! CHECK: %[[B:.*]] = fir.alloca !fir.class<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>> {bindc_name = "b", uniq_name = "_QMpolymorphic_testFclass_with_entryEb"}
+
+! CHECK-LABEL: func.func @_QMpolymorphic_testPd(
+! CHECK-SAME: %[[B:.*]]: !fir.class<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>> {fir.bindc_name = "b"}) {
+! CHECK: %[[A:.*]] = fir.alloca !fir.class<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>> {bindc_name = "a", uniq_name = "_QMpolymorphic_testFclass_with_entryEa"}
+
 end module
 
 program test