diff --git a/paddle/fluid/memory/allocation/retry_allocator_test.cc b/paddle/fluid/memory/allocation/retry_allocator_test.cc
index 670dc9ffba2e8fae4b84246eb35bd3f047b02693..11a8dfdc472d6b6cdec2b3f618aeb7065a10447b 100644
--- a/paddle/fluid/memory/allocation/retry_allocator_test.cc
+++ b/paddle/fluid/memory/allocation/retry_allocator_test.cc
@@ -127,7 +127,7 @@ TEST(RetryAllocator, RetryAllocatorLastAllocFailure) {
   {
     platform::CUDAPlace p(0);
     RetryAllocator allocator(std::make_shared<CUDAAllocator>(p), retry_ms);
-    size_t allocate_size = -1UL;  // Very large number
+    size_t allocate_size = (static_cast<size_t>(1) << 40);  // Very large number
     try {
       auto allocation = allocator.Allocate(allocate_size);
       ASSERT_TRUE(false);
diff --git a/paddle/fluid/memory/detail/system_allocator_test.cc b/paddle/fluid/memory/detail/system_allocator_test.cc
index ed5022cac694368347d9990f17a81fdb2c84f301..34bb40d549dff1d711cd8924630cdf528f41ed76 100644
--- a/paddle/fluid/memory/detail/system_allocator_test.cc
+++ b/paddle/fluid/memory/detail/system_allocator_test.cc
@@ -73,7 +73,7 @@ TEST(CUDAPinnedAllocator, Alloc) {
 TEST(GPUAllocator, AllocFailure) {
   paddle::memory::detail::GPUAllocator allocator(0);
   size_t index;
-  size_t alloc_size = -1UL;  // very large size
+  size_t alloc_size = (static_cast<size_t>(1) << 40);  // Very large number
   try {
     allocator.Alloc(&index, alloc_size);
     ASSERT_TRUE(false);