diff --git a/flang/lib/Optimizer/Builder/Runtime/Allocatable.cpp b/flang/lib/Optimizer/Builder/Runtime/Allocatable.cpp
--- a/flang/lib/Optimizer/Builder/Runtime/Allocatable.cpp
+++ b/flang/lib/Optimizer/Builder/Runtime/Allocatable.cpp
@@ -24,7 +24,8 @@
   mlir::Value sourceLine{
       fir::factory::locationToLineNo(builder, loc, fTy.getInput(6))};
   mlir::Value declaredTypeDesc;
-  if (fir::isPolymorphicType(from.getType())) {
+  if (fir::isPolymorphicType(from.getType()) &&
+      !fir::isUnlimitedPolymorphicType(from.getType())) {
     fir::ClassType clTy =
         fir::dyn_cast_ptrEleTy(from.getType()).dyn_cast<fir::ClassType>();
     mlir::Type derivedType = fir::unwrapInnerType(clTy.getEleTy());
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
@@ -1001,6 +1001,19 @@
 ! CHECK: %[[TYPE_DESC_CONV:.*]] = fir.convert %[[TYPE_DESC]] : (!fir.tdesc<!fir.type<_QMpolymorphic_testTp1{a:i32,b:i32}>>) -> !fir.ref<none>
 ! CHECK: %{{.*}} = fir.call @_FortranAMoveAlloc(%[[B_CONV]], %[[A_CONV]], %[[TYPE_DESC_CONV]], %{{.*}}, %{{.*}}, %{{.*}}, %{{.*}}) {{.*}} : (!fir.ref<!fir.box<none>>, !fir.ref<!fir.box<none>>, !fir.ref<none>, i1, !fir.box<none>, !fir.ref<i8>, i32) -> i32
 
+  subroutine move_alloc_unlimited_poly(a, b)
+    class(*), allocatable :: a, b
+
+    call move_alloc(a, b)
+  end subroutine
+
+! CHECK-LABEL: func.func @_QMpolymorphic_testPmove_alloc_unlimited_poly(
+! CHECK-SAME: %[[A:.*]]: !fir.ref<!fir.class<!fir.heap<none>>> {fir.bindc_name = "a"}, %[[B:.*]]: !fir.ref<!fir.class<!fir.heap<none>>> {fir.bindc_name = "b"}) {
+! CHECK: %[[NULL:.*]] = fir.zero_bits !fir.ref<none>
+! CHECK: %[[B_CONV:.*]] = fir.convert %[[B]] : (!fir.ref<!fir.class<!fir.heap<none>>>) -> !fir.ref<!fir.box<none>>
+! CHECK: %[[A_CONV:.*]] = fir.convert %[[A]] : (!fir.ref<!fir.class<!fir.heap<none>>>) -> !fir.ref<!fir.box<none>>
+! CHECK: %{{.*}} = fir.call @_FortranAMoveAlloc(%[[B_CONV]], %[[A_CONV]], %[[NULL]], %{{.*}}, %{{.*}}, %{{.*}}, %{{.*}}) {{.*}} : (!fir.ref<!fir.box<none>>, !fir.ref<!fir.box<none>>, !fir.ref<none>, i1, !fir.box<none>, !fir.ref<i8>, i32) -> i32
+
 end module
 
 program test