diff --git a/hw/pass-through.c b/hw/pass-through.c
index ecb3d6f..3381782 100644
--- a/hw/pass-through.c
+++ b/hw/pass-through.c
@@ -4258,11 +4258,23 @@ static int setup_vga_pt(void)
         goto out;
     }
 
-    /* Adjust the bios checksum */
+    /* Validate the bios checksum */
     for ( c = (char*)bios; c < ((char*)bios + bios_size); c++ )
         checksum += *c;
     if ( checksum )
-        bios[bios_size - 1] -= checksum;
+    {
+        if ( igd_passthru )
+        {
+            bios[bios_size - 1] -= checksum;
+            PT_LOG("vga bios checksum is adjusted!\n");
+        }
+        else
+        {
+            PT_LOG("vga bios checksum is invalid!\n");
+            rc = -1;
+            goto out;
+        }
+    }
 
     cpu_physical_memory_rw(0xc0000, bios, bios_size, 1);