diff --git a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c
index f9c6f5c553..a96e0e5275 100644
--- a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c
+++ b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c
@@ -54,7 +54,7 @@ QemuFlashPtr (
   IN        UINTN                               Offset
   )
 {
-  return mFlashBase + (Lba * mFdBlockSize) + Offset;
+  return mFlashBase + ((UINTN)Lba * mFdBlockSize) + Offset;
 }