diff --git a/MdePkg/Library/BaseMemoryLib/SetMem.c b/MdePkg/Library/BaseMemoryLib/SetMem.c
index 69fa265ba2..dee44f61ce 100644
--- a/MdePkg/Library/BaseMemoryLib/SetMem.c
+++ b/MdePkg/Library/BaseMemoryLib/SetMem.c
@@ -46,7 +46,7 @@ InternalMemSetMem (
   volatile UINT8                    *Pointer;
 
   Pointer = (UINT8*)Buffer;
-  while (Size-- != 0) {
+  while (Length-- != 0) {
     *(Pointer++) = Value;
   }
   return Buffer;