diff --git a/driver/common/vx_utils.h b/driver/common/vx_utils.h
index b86c75af..0bac7394 100644
--- a/driver/common/vx_utils.h
+++ b/driver/common/vx_utils.h
@@ -8,4 +8,5 @@ bool is_aligned(uint64_t addr, uint64_t alignment);
 
 #define CACHE_BLOCK_SIZE    64
 #define ALLOC_BASE_ADDR     0x00000000
-#define LOCAL_MEM_SIZE      4294967296     // 4 GB 
\ No newline at end of file
+#define LOCAL_MEM_SIZE      4294967296     // 4 GB 
+#define DEVICE_MAX_ADDR     0xfffffffful
diff --git a/driver/rtlsim/vortex.cpp b/driver/rtlsim/vortex.cpp
index 8e180339..7b241e9a 100644
--- a/driver/rtlsim/vortex.cpp
+++ b/driver/rtlsim/vortex.cpp
@@ -86,7 +86,7 @@ public:
 
     int upload(const void* src, uint64_t dest_addr, uint64_t size, uint64_t src_offset) {
         uint64_t asize = aligned_size(size, CACHE_BLOCK_SIZE);
-        if (dest_addr + asize > LOCAL_MEM_SIZE)
+        if (dest_addr + asize > DEVICE_MAX_ADDR)
             return -1;
 
         /*printf("VXDRV: upload %ld bytes from 0x%lx:", size, uintptr_t((uint8_t*)src + src_offset));
@@ -104,7 +104,7 @@ public:
 
     int download(void* dest, uint64_t src_addr, uint64_t size, uint64_t dest_offset) {
         uint64_t asize = aligned_size(size, CACHE_BLOCK_SIZE);
-        if (src_addr + asize > LOCAL_MEM_SIZE)
+        if (src_addr + asize > DEVICE_MAX_ADDR)
             return -1;
 
         ram_.read((uint8_t*)dest + dest_offset, src_addr, asize);
@@ -352,4 +352,4 @@ extern int vx_ready_wait(vx_device_h hdevice, uint64_t timeout) {
     vx_device *device = ((vx_device*)hdevice);
 
     return device->wait(timeout);
-}
\ No newline at end of file
+}
diff --git a/driver/simx/vortex.cpp b/driver/simx/vortex.cpp
index 95957cc2..05d0287b 100644
--- a/driver/simx/vortex.cpp
+++ b/driver/simx/vortex.cpp
@@ -93,7 +93,7 @@ public:
 
     int upload(const void* src, uint64_t dest_addr, uint64_t size, uint64_t src_offset) {
         uint64_t asize = aligned_size(size, CACHE_BLOCK_SIZE);
-        if (dest_addr + asize > LOCAL_MEM_SIZE)
+        if (dest_addr + asize > DEVICE_MAX_ADDR)
             return -1;
 
         ram_.write((const uint8_t*)src + src_offset, dest_addr, asize);
@@ -108,7 +108,7 @@ public:
 
     int download(void* dest, uint64_t src_addr, uint64_t size, uint64_t dest_offset) {
         uint64_t asize = aligned_size(size, CACHE_BLOCK_SIZE);
-        if (src_addr + asize > LOCAL_MEM_SIZE)
+        if (src_addr + asize > DEVICE_MAX_ADDR)
             return -1;
 
         ram_.read((uint8_t*)dest + dest_offset, src_addr, asize);
@@ -354,4 +354,4 @@ extern int vx_ready_wait(vx_device_h hdevice, uint64_t timeout) {
     vx_device *device = ((vx_device*)hdevice);
 
     return device->wait(timeout);
-}
\ No newline at end of file
+}