diff --git a/drivers/char/mem/src/mem.c b/drivers/char/mem/src/mem.c
index 8a4e96e9..ea6fbb7e 100644
--- a/drivers/char/mem/src/mem.c
+++ b/drivers/char/mem/src/mem.c
@@ -61,7 +61,7 @@ static ssize_t MemMap(struct file *filep, LosVmMapRegion *region)
     VADDR_T vaddr = region->range.base;
     LosVmSpace *space = LOS_SpaceGet(vaddr);
 
-    if ((paddr >= SYS_MEM_BASE) && (paddr < SYS_MEM_END)) {
+    if (((paddr + size) >= SYS_MEM_BASE) && (paddr < SYS_MEM_END)) {
         return -EINVAL;
     }