diff --git a/flang/include/flang/Optimizer/Dialect/FIRTypes.td b/flang/include/flang/Optimizer/Dialect/FIRTypes.td
--- a/flang/include/flang/Optimizer/Dialect/FIRTypes.td
+++ b/flang/include/flang/Optimizer/Dialect/FIRTypes.td
@@ -610,8 +610,8 @@
     AnyBoxLike.predicate, FunctionType.predicate]>,
     "any reference or box like">;
 def AnyRefOrBox : TypeConstraint<Or<[fir_ReferenceType.predicate,
-    fir_HeapType.predicate, fir_PointerType.predicate, fir_BoxType.predicate]>,
-    "any reference or box">;
+    fir_HeapType.predicate, fir_PointerType.predicate,
+    IsBaseBoxTypePred]>, "any reference or box">;
 
 def AnyShapeLike : TypeConstraint<Or<[fir_ShapeType.predicate,
     fir_ShapeShiftType.predicate]>, "any legal shape type">;
diff --git a/flang/test/Lower/polymorphic.f90 b/flang/test/Lower/polymorphic.f90
new file mode 100644
--- /dev/null
+++ b/flang/test/Lower/polymorphic.f90
@@ -0,0 +1,30 @@
+! RUN: bbc -polymorphic-type -emit-fir %s -o - | FileCheck %s
+
+! Tests various aspect of the lowering of polymorphic entities.
+
+module polymorphic_test
+  type p1
+    integer :: a
+    integer :: b
+  end type
+
+  type, extends(p1) :: p2
+    real :: c
+  end type
+
+  contains
+
+  ! Test correct access to polymorphic entity component.
+  subroutine component_access(p)
+    class(p1) :: p
+    print*, p%a
+  end subroutine
+
+! CHECK-LABEL: func.func @_QMpolymorphic_testPcomponent_access(
+! CHECK-SAME: %[[P:.*]]: !fir.class<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>> {fir.bindc_name = "p"}) {
+! CHECK: %[[FIELD:.*]] = fir.field_index a, !fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>
+! CHECK: %[[COORD:.*]] = fir.coordinate_of %[[P]], %[[FIELD]] : (!fir.class<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>>, !fir.field) -> !fir.ref<i32>
+! CHECK: %[[LOAD:.*]] = fir.load %[[COORD]] : !fir.ref<i32>
+! CHECK: %{{.*}} = fir.call @_FortranAioOutputInteger32(%{{.*}}, %[[LOAD]]) : (!fir.ref<i8>, i32) -> i1
+
+end module