diff --git a/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c b/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c
index 7a6d3153ec..9f9babc9cc 100644
--- a/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c
+++ b/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c
@@ -340,7 +340,7 @@ FvbProtocolEraseBlocks (
       break;
     }
 
-    NumOfLba = VA_ARG (args, UINT32);
+    NumOfLba = VA_ARG (args, UINTN);
 
     //
     // Check input parameters