diff --git a/flang/lib/Optimizer/Transforms/CUFAddConstructor.cpp b/flang/lib/Optimizer/Transforms/CUFAddConstructor.cpp
index 7cdb2f7ffe27d..dd204126be5db 100644
--- a/flang/lib/Optimizer/Transforms/CUFAddConstructor.cpp
+++ b/flang/lib/Optimizer/Transforms/CUFAddConstructor.cpp
@@ -11,11 +11,13 @@
 #include "flang/Optimizer/Builder/Runtime/RTBuilder.h"
 #include "flang/Optimizer/Builder/Todo.h"
 #include "flang/Optimizer/CodeGen/Target.h"
+#include "flang/Optimizer/CodeGen/TypeConverter.h"
 #include "flang/Optimizer/Dialect/CUF/CUFOps.h"
 #include "flang/Optimizer/Dialect/FIRAttr.h"
 #include "flang/Optimizer/Dialect/FIRDialect.h"
 #include "flang/Optimizer/Dialect/FIROps.h"
 #include "flang/Optimizer/Dialect/FIROpsSupport.h"
+#include "flang/Optimizer/Dialect/FIRType.h"
 #include "flang/Optimizer/Support/DataLayout.h"
 #include "flang/Optimizer/Transforms/CUFCommon.h"
 #include "flang/Runtime/CUDA/registration.h"
@@ -84,6 +86,8 @@ struct CUFAddConstructor
       auto registeredMod = builder.create<cuf::RegisterModuleOp>(
           loc, llvmPtrTy, mlir::SymbolRefAttr::get(ctx, gpuMod.getName()));
 
+      fir::LLVMTypeConverter typeConverter(mod, /*applyTBAA=*/false,
+                                           /*forceUnifiedTBAATree=*/false, *dl);
       // Register kernels
       for (auto func : gpuMod.getOps<mlir::gpu::GPUFuncOp>()) {
         if (func.isKernel()) {
@@ -115,17 +119,25 @@ struct CUFAddConstructor
               fir::factory::createStringLiteral(builder, loc, gblNameStr));
 
           // Global variable size
-          auto sizeAndAlign = fir::getTypeSizeAndAlignmentOrCrash(
-              loc, globalOp.getType(), *dl, kindMap);
-          auto size =
-              builder.createIntegerConstant(loc, idxTy, sizeAndAlign.first);
+          std::optional<uint64_t> size;
+          if (auto boxTy =
+                  mlir::dyn_cast<fir::BaseBoxType>(globalOp.getType())) {
+            mlir::Type structTy = typeConverter.convertBoxTypeAsStruct(boxTy);
+            size = dl->getTypeSizeInBits(structTy) / 8;
+          }
+          if (!size) {
+            size = fir::getTypeSizeAndAlignmentOrCrash(loc, globalOp.getType(),
+                                                       *dl, kindMap)
+                       .first;
+          }
+          auto sizeVal = builder.createIntegerConstant(loc, idxTy, *size);
 
           // Global variable address
           mlir::Value addr = builder.create<fir::AddrOfOp>(
               loc, globalOp.resultType(), globalOp.getSymbol());
 
           llvm::SmallVector<mlir::Value> args{fir::runtime::createArguments(
-              builder, loc, fTy, registeredMod, addr, gblName, size)};
+              builder, loc, fTy, registeredMod, addr, gblName, sizeVal)};
           builder.create<fir::CallOp>(loc, func, args);
         } break;
         case cuf::DataAttribute::Managed:
diff --git a/flang/test/Fir/CUDA/cuda-constructor-2.f90 b/flang/test/Fir/CUDA/cuda-constructor-2.f90
index 378dabbb7c7e7..99386abc4fafd 100644
--- a/flang/test/Fir/CUDA/cuda-constructor-2.f90
+++ b/flang/test/Fir/CUDA/cuda-constructor-2.f90
@@ -3,6 +3,12 @@
 module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<!llvm.ptr, dense<64> : vector<4xi64>>, #dlti.dl_entry<!llvm.ptr<271>, dense<32> : vector<4xi64>>, #dlti.dl_entry<!llvm.ptr<270>, dense<32> : vector<4xi64>>, #dlti.dl_entry<f128, dense<128> : vector<2xi64>>, #dlti.dl_entry<f64, dense<64> : vector<2xi64>>, #dlti.dl_entry<f80, dense<128> : vector<2xi64>>, #dlti.dl_entry<f16, dense<16> : vector<2xi64>>, #dlti.dl_entry<i32, dense<32> : vector<2xi64>>, #dlti.dl_entry<i16, dense<16> : vector<2xi64>>, #dlti.dl_entry<i128, dense<128> : vector<2xi64>>, #dlti.dl_entry<i8, dense<8> : vector<2xi64>>, #dlti.dl_entry<!llvm.ptr<272>, dense<64> : vector<4xi64>>, #dlti.dl_entry<i64, dense<64> : vector<2xi64>>, #dlti.dl_entry<i1, dense<8> : vector<2xi64>>, #dlti.dl_entry<"dlti.endianness", "little">, #dlti.dl_entry<"dlti.stack_alignment", 128 : i64>>, fir.defaultkind = "a1c4d8i4l4r4", fir.kindmap = "", gpu.container_module, llvm.data_layout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128", llvm.ident = "flang version 20.0.0 (https://github.com/llvm/llvm-project.git cae351f3453a0a26ec8eb2ddaf773c24a29d929e)", llvm.target_triple = "x86_64-unknown-linux-gnu"} {
 
   fir.global @_QMmtestsEn(dense<[3, 4, 5, 6, 7]> : tensor<5xi32>) {data_attr = #cuf.cuda<device>} : !fir.array<5xi32>
+  fir.global @_QMmtestsEndev {data_attr = #cuf.cuda<device>} : !fir.box<!fir.heap<!fir.array<?xi32>>> {
+    %c0 = arith.constant 0 : index
+    %0 = fir.zero_bits !fir.heap<!fir.array<?xi32>>
+    %1 = fircg.ext_embox %0(%c0) {allocator_idx = 2 : i32} : (!fir.heap<!fir.array<?xi32>>, index) -> !fir.box<!fir.heap<!fir.array<?xi32>>>
+    fir.has_value %1 : !fir.box<!fir.heap<!fir.array<?xi32>>>
+  }
 
   gpu.module @cuda_device_mod [#nvvm.target] {
   }
@@ -18,5 +24,9 @@ module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<!llvm.ptr, dense<
 // CHECK-DAG: %[[VAR_ADDR2:.*]] = fir.convert %[[VAR_ADDR]] : (!fir.ref<!fir.array<5xi32>>) -> !fir.ref<i8>
 // CHECK-DAG: %[[VAR_NAME2:.*]] = fir.convert %[[VAR_NAME]] : (!fir.ref<!fir.char<1,12>>) -> !fir.ref<i8>
 // CHECK-DAG: %[[CST:.*]] = arith.constant 20 : index
-// CHECK-DAG %[[CST2:.*]] = fir.convert %[[CST]] : (index) -> i64
-// CHECK fir.call @_FortranACUFRegisterVariable(%[[MODULE2]], %[[VAR_ADDR2]], %[[VAR_NAME2]], %[[CST2]]) : (!fir.ref<!fir.llvm_ptr<i8>>, !fir.ref<i8>, !fir.ref<i8>, i64) -> none
+// CHECK-DAG: %[[CST2:.*]] = fir.convert %[[CST]] : (index) -> i64
+// CHECK-DAG: fir.call @_FortranACUFRegisterVariable(%[[MODULE2]], %[[VAR_ADDR2]], %[[VAR_NAME2]], %[[CST2]]) : (!fir.ref<!fir.llvm_ptr<i8>>, !fir.ref<i8>, !fir.ref<i8>, i64) -> none
+// CHECK-DAG: %[[BOX:.*]] = fir.address_of(@_QMmtestsEndev) : !fir.ref<!fir.box<!fir.heap<!fir.array<?xi32>>>>
+// CHECK-DAG: %[[BOXREF:.*]] = fir.convert %[[BOX]] : (!fir.ref<!fir.box<!fir.heap<!fir.array<?xi32>>>>) -> !fir.ref<i8>
+// CHECK-DAG: fir.call @_FortranACUFRegisterVariable(%[[MODULE:.*]], %[[BOXREF]], %{{.*}}, %{{.*}}) 
+//
diff --git a/flang/test/Fir/CUDA/cuda-register-func.fir b/flang/test/Fir/CUDA/cuda-register-func.fir
index 6b0cbfd3aca63..25ab8dd786a4e 100644
--- a/flang/test/Fir/CUDA/cuda-register-func.fir
+++ b/flang/test/Fir/CUDA/cuda-register-func.fir
@@ -1,6 +1,6 @@
 // RUN: fir-opt --cuf-add-constructor %s | FileCheck %s
 
-module attributes {gpu.container_module} {
+module attributes {dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<!llvm.ptr, dense<64> : vector<4xi64>>, #dlti.dl_entry<!llvm.ptr<271>, dense<32> : vector<4xi64>>, #dlti.dl_entry<!llvm.ptr<270>, dense<32> : vector<4xi64>>, #dlti.dl_entry<f128, dense<128> : vector<2xi64>>, #dlti.dl_entry<f64, dense<64> : vector<2xi64>>, #dlti.dl_entry<f80, dense<128> : vector<2xi64>>, #dlti.dl_entry<f16, dense<16> : vector<2xi64>>, #dlti.dl_entry<i32, dense<32> : vector<2xi64>>, #dlti.dl_entry<i16, dense<16> : vector<2xi64>>, #dlti.dl_entry<i128, dense<128> : vector<2xi64>>, #dlti.dl_entry<i8, dense<8> : vector<2xi64>>, #dlti.dl_entry<!llvm.ptr<272>, dense<64> : vector<4xi64>>, #dlti.dl_entry<i64, dense<64> : vector<2xi64>>, #dlti.dl_entry<i1, dense<8> : vector<2xi64>>, #dlti.dl_entry<"dlti.endianness", "little">, #dlti.dl_entry<"dlti.stack_alignment", 128 : i64>>, fir.defaultkind = "a1c4d8i4l4r4", fir.kindmap = "", gpu.container_module, llvm.data_layout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128", llvm.ident = "flang version 20.0.0 (https://github.com/llvm/llvm-project.git cae351f3453a0a26ec8eb2ddaf773c24a29d929e)", llvm.target_triple = "x86_64-unknown-linux-gnu"} {
   gpu.module @cuda_device_mod {
     gpu.func @_QPsub_device1() kernel {
       gpu.return