diff --git a/MdePkg/Include/Library/UefiRuntimeLib.h b/MdePkg/Include/Library/UefiRuntimeLib.h
index 54be1017df..3d5f721012 100644
--- a/MdePkg/Include/Library/UefiRuntimeLib.h
+++ b/MdePkg/Include/Library/UefiRuntimeLib.h
@@ -344,7 +344,7 @@ EfiResetSystem (
   IN EFI_RESET_TYPE               ResetType,
   IN EFI_STATUS                   ResetStatus,
   IN UINTN                        DataSize,
-  IN CHAR16                       *ResetData
+  IN VOID                         *ResetData OPTIONAL
   );
 
 /**
diff --git a/MdePkg/Library/UefiRuntimeLib/RuntimeService.c b/MdePkg/Library/UefiRuntimeLib/RuntimeService.c
index 1d2c5d413c..4626606292 100644
--- a/MdePkg/Library/UefiRuntimeLib/RuntimeService.c
+++ b/MdePkg/Library/UefiRuntimeLib/RuntimeService.c
@@ -55,7 +55,7 @@ EfiResetSystem (
   IN EFI_RESET_TYPE               ResetType,
   IN EFI_STATUS                   ResetStatus,
   IN UINTN                        DataSize,
-  IN CHAR16                       *ResetData
+  IN VOID                         *ResetData OPTIONAL
   )
 {
   mRT->ResetSystem (ResetType, ResetStatus, DataSize, ResetData);