diff --git a/flang/lib/Lower/CallInterface.cpp b/flang/lib/Lower/CallInterface.cpp
--- a/flang/lib/Lower/CallInterface.cpp
+++ b/flang/lib/Lower/CallInterface.cpp
@@ -251,7 +251,8 @@
     if (std::optional<Fortran::evaluate::ExtentExpr> length =
             dynamicType.GetCharLength())
       visitor(toEvExpr(*length));
-  } else if (dynamicType.category() == common::TypeCategory::Derived) {
+  } else if (dynamicType.category() == common::TypeCategory::Derived &&
+             !dynamicType.IsUnlimitedPolymorphic()) {
     const Fortran::semantics::DerivedTypeSpec &derivedTypeSpec =
         dynamicType.GetDerivedTypeSpec();
     if (Fortran::semantics::CountLenParameters(derivedTypeSpec) > 0)
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
@@ -99,4 +99,21 @@
 ! CHECK-LABEL: func.func @_QMpolymorphic_testPpolymorphic_to_nonpolymorphic
 ! Just checking that FIR is generated without error.
 
+! Test that lowering does not crash for function return with unlimited
+! polymoprhic value.
+
+  function up_ret()
+    class(*), pointer :: up_ret(:)
+  end function
+
+! CHECK-LABEL: func.func @_QMpolymorphic_testPup_ret() -> !fir.class<!fir.ptr<!fir.array<?xnone>>> {
+
+  subroutine call_up_ret()
+    class(*), pointer :: p(:)
+    p => up_ret()
+  end subroutine
+
+! CHECK-LABEL: func.func @_QMpolymorphic_testPcall_up_ret() {
+! CHECK:         %{{.*}} = fir.call @_QMpolymorphic_testPup_ret() {{.*}} : () -> !fir.class<!fir.ptr<!fir.array<?xnone>>>
+
 end module