diff --git a/DuetPkg/FvbRuntimeService/FWBlockService.c b/DuetPkg/FvbRuntimeService/FWBlockService.c
index e0ddbd5312..bc663273d4 100644
--- a/DuetPkg/FvbRuntimeService/FWBlockService.c
+++ b/DuetPkg/FvbRuntimeService/FWBlockService.c
@@ -991,7 +991,7 @@ Returns:
       break;
     }
 
-    NumOfLba = VA_ARG (args, UINT32);
+    NumOfLba = VA_ARG (args, UINTN);
 
     //
     // Check input parameters
@@ -1011,7 +1011,7 @@ Returns:
       break;
     }
 
-    NumOfLba = VA_ARG (args, UINT32);
+    NumOfLba = VA_ARG (args, UINTN);
 
     while (NumOfLba > 0) {
       Status = FvbEraseBlock (FvbDevice->Instance, StartingLba, mFvbModuleGlobal, EfiGoneVirtual ());