diff --git a/MdePkg/Include/Library/DevicePathLib.h b/MdePkg/Include/Library/DevicePathLib.h
index 805ab50704..eb9de5a873 100644
--- a/MdePkg/Include/Library/DevicePathLib.h
+++ b/MdePkg/Include/Library/DevicePathLib.h
@@ -172,8 +172,8 @@ IsDevicePathEndInstance (
 **/
 UINT16
 SetDevicePathNodeLength (
-  IN VOID   *Node,
-  IN UINTN  Length
+  IN OUT VOID  *Node,
+  IN UINTN     Length
   );
 
 /**
@@ -194,7 +194,7 @@ SetDevicePathNodeLength (
 **/
 VOID
 SetDevicePathEndNode (
-  IN VOID  *Node
+  OUT VOID  *Node
   );
 
 /**
diff --git a/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.c b/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.c
index edc03f0e6b..b2602e2a58 100644
--- a/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.c
+++ b/MdePkg/Library/UefiDevicePathLib/UefiDevicePathLib.c
@@ -221,8 +221,8 @@ IsDevicePathEndInstance (
 **/
 UINT16
 SetDevicePathNodeLength (
-  IN VOID   *Node,
-  IN UINTN  NodeLength
+  IN OUT VOID  *Node,
+  IN UINTN     NodeLength
   )
 {
   ASSERT (Node != NULL);
@@ -248,7 +248,7 @@ SetDevicePathNodeLength (
 **/
 VOID
 SetDevicePathEndNode (
-  IN VOID  *Node
+  OUT VOID  *Node
   )
 {
   ASSERT (Node != NULL);
diff --git a/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c b/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c
index 08a0191c14..8f2488a3b2 100644
--- a/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c
+++ b/MdePkg/Library/UefiDevicePathLibDevicePathProtocol/UefiDevicePathLib.c
@@ -250,8 +250,8 @@ IsDevicePathEndInstance (
 **/
 UINT16
 SetDevicePathNodeLength (
-  IN VOID   *Node,
-  IN UINTN  NodeLength
+  IN OUT VOID  *Node,
+  IN UINTN     NodeLength
   )
 {
   ASSERT (Node != NULL);
@@ -277,7 +277,7 @@ SetDevicePathNodeLength (
 **/
 VOID
 SetDevicePathEndNode (
-  IN VOID  *Node
+  OUT VOID  *Node
   )
 {
   ASSERT (Node != NULL);