diff --git a/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c b/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c
index 468baa5a76..afbd590787 100644
--- a/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c
+++ b/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c
@@ -1003,8 +1003,9 @@ DevPathToTextUsbWWID (
     //
     // In case no NULL terminator in SerialNumber, create a new one with NULL terminator
     //
-    NewStr = AllocateCopyPool ((Length + 1) * sizeof (CHAR16), SerialNumberStr);
+    NewStr = AllocatePool ((Length + 1) * sizeof (CHAR16));
     ASSERT (NewStr != NULL);
+    CopyMem (NewStr, SerialNumberStr, Length * sizeof (CHAR16));
     NewStr[Length]  = 0;
     SerialNumberStr = NewStr;
   }